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312B – Practice questions– p.1
Type B
1.
if only a, b and c are correct
2.
if only a and c are correct
3.
if only b and d are correct
4.
if only d is correct
5.
if all or none are correct
1.1. In adult mammals, the quantity of oxygen convection by pulmonary ventilation depends on
a. pulmonary ventilation itself
b. partial pressure of alveolar oxygen
c. partial pressure of oxygen in the inspired air
d. temperature of the inspired air
1.2. The fundamental physical process(es) at the basis of all forms of gas exchange is/are
a. conduction
b. convection
c. active transport
d. diffusion
1.3. The quantity of a gas that diffuses into a liquid over a given time period depends on
a. diffusion coefficient of the gas
b. temperature
c. the solubility coefficient
d. concentration gradient between the two media
1.4. (Type A) - Gases in liquids diffuse according to
a. partial pressure gradients
b. concentration gradients
c. efficiency of active pumps
d. temperature gradients
e. all of the above
1.5. (Type A). An increase in the partial pressure of carbon dioxide in the alveoli (PACO2)
changes the quantity of oxygen convection by pulmonary ventilation because
a. reduces the quantity of oxygen in the alveoli
b. changes the level of pulmonary ventilation
c. interferes with the alveolar-capillary oxygen exchange
d. increases the work of breathing
e. Bohr effect on the hemoglobin-oxygen dissociation curve
1.6. Negative pressure ventilation (or ‘aspiration pump’) as the sole means of gas convection is
most commonly found in
a. birds
b. fishes
c. mammals
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312B – Practice questions– p.2
d. frogs
1.7. In mammals, the computation of the oxygen used per unit time (oxygen consumption)
requires knowledge of
a. concentration of the inspired oxygen
b. pulmonary ventilation
c. pulmonary extraction coefficient
d. respiratory exchange ratio
[Fick equation applied to the respiratory system]
1.8. The following is/are characteristic(s) of the mammalian design of the respiratory system
a. a countercurrent air-blood exchange
b. the possibility of lowering the dead space to a minimal fraction (<2%) of tidal volume
c. values of alveolar partial pressure of oxygen close to the inspired partial pressure value
d. distortion of the chest wall during diaphragmatic contraction
1.9. The following is/are characteristic(s) of the gas exchange process in a fish
a. countercurrent air-blood exchange
b. dead space of about half tidal volume
c. arterial partial pressure of oxygen almost identical to the inspired partial pressure
d. diaphragmatic negative pressure ventilation
1.10. The physical process of oxygen transfer from alveoli to pulmonary capillaries depends on
a. active transport
b. hemoglobin concentration
c. pulmonary blood flow
d. gas diffusion
1.11. In normoxic conditions and constant food intake, the following is (are) expected to be
representative of the rate of the metabolic processes
a. heat production
b. carbon dioxide production
c. water production
d. oxygen consumption
1.12. (Type A) The relationship between carbon dioxide production and oxygen consumption at
the tissue level is called
a. ventilator equivalent
b. respiratory exchange ratio
c. respiratory quotient
d. gas exchange
e. exchange efficiency
1.13. At the body temperature of 37°C and sea level conditions (24°C ambient temperature and
50% relative humidity), the partial pressure gradient of carbon dioxide between mitochondria
and environment
a. is about half that of water vapor
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312B – Practice questions– p.3
b. decreases to about half during hyperoxic breathing
c. almost doubles during hypoxia
d. is much less than the partial pressure gradient of oxygen between environment and
mitochondria.
1.14. In humans, changes in body temperature modify
a. pulmonary ventilation
b. the solubility of gases
c. the gas diffusion coefficients
d. metabolic rate
1.15. ‘Buccal’ respiration
a. is common in frogs
b. is synchronized with the control of the nasal openings
c. favors homogeneous expansion of the lungs
d. requires diaphragmatic contraction
1.16. In adult humans during resting breathing at sea level the O2 partial pressure in the
arterialized blood is lower than the inspired O2 pressure. The reason(s) for this is/are
a. tidal volume cannot exceed 2-3 liters
b. the partial pressure of O2 in the alveoli is lower than in the inspired air
c. breathing frequency cannot exceed 100 breaths/min
d. presence of a dead space
1.17. Gas exchange in birds is more efficient than in mammals because
a. presence of air sacs
b. absence of diaphragm
c. higher body temperature
d. cross-current design for gas exchange
1.18. the allometric function of oxygen consumption has the same exponent as that of
a. tidal volume
b. pulmonary ventilation
c. breathing frequency
d. metabolic rate
1.19. Gas exchange in fishes (through gills) and in mammals (through lungs) have in common
a. diffusion as the main mechanism for gas exchange
b. the same dead space-tidal volume ratio
c. convection as a mechanism of oxygen-transport toward the gas exchange barrier
d. oxygen exchange as efficient as carbon dioxide exchange
1.20. In an adult healthy subject, during resting breathing in normoxia
a. the expired air has more than 10% carbon dioxide
b. the expired air has more than 10% oxygen
c. oxygen consumption equals carbon dioxide production
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312B – Practice questions– p.4
d. alveolar ventilation is about 2/3 of minute ventilation
1.21. In large-size mammals (by comparison to small-size mammals) the geometrical
considerations regarding spheres of different sizes ("Surface Law") is considered a possible
contributing factor to explain their
a. greater mass-specific tidal volumes (VT/kg)
b. smaller mass-specific oxygen consumption (VO2/kg)
c. same body temperature
d. smaller mass-specific pulmonary ventilation (VE/kg)
[Body surface versus body mass in heat loss and heat gain]
1.22. Alveolar ventilation
a. is the quantity of air passing through the alveolar region per unit time
b. in absence of dead space, it is the same as pulmonary ventilation
c. is responsible for gas exchange
d. equals the product of tidal volume and breathing frequency
1.23. The ventilatory equivalent (ventilation-oxygen consumption ratio)
a. has approximately similar values among mammalian species at rest
b. increases during hypoxia
c. is lower than the ratio between pulmonary ventilation and carbon dioxide production
d. increases during moderate exercise
1.24. Air sacs are commonly found in
a. turtles
b. fish
c. mammals
d, snails
1.25. In addition to mammals, the diaphragm is a muscle typically found in
a. birds
b. lizards
c. frogs
d. turtles
1.26. Diffusion is the mechanism of gas transfer
a. in avian eggs, between the environment and the chorioallantoic membrane
b. in mammals, between tissue capillaries and cells
c. in birds, between air capillaries and vascular capillaries
d. in fish, between the lamellae of the gills and the gill capillaries
1.27. Aspiration pump as a mechanism of air convection into the gas exchange area is typical of
a. lung fish
b. birds
c. crocodiles
d. insects
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312B – Practice questions– p.5
1.28. The quantity of gas carried by a liquid medium over a period of time depends on
a. partial pressure of the gas
b. flow rate of the liquid
c. solubility coefficient of the gas in the liquid
d. flow-resistance encountered by the liquid
1.29. In perfect steady state, the rate of metabolism can be expressed by
a. oxygen consumption
b. water production
c. carbon dioxide production
d. cardiac output
1.30. In healthy adult humans at rest the O2 partial pressure in the arterialized blood is slightly
lower than the alveolar O2 pressure. The reason for this could be attributed to
a. intrapulmonary shunt
b. presence of a dead space
c. ventilation-perfusion inequalities
d. diffusion limitation
1.31. Which of the following is/are CORRECT concerning the diffusion of O2 across the
alveolar-capillary barrier?
a. doubling the thickness of the barrier would cut the total flow of O2 in half.
b. doubling the area of the barrier would double the total flow of O2.
c. an increase in the alveolar concentration of O2 increases the total flow of O2 across the barrier.
d. increasing the arterial concentration of O2 would decrease the total O2 flow
1.32. (Type A) If the inspired fractional oxygen concentration (FIO2) is 0.21, and its
correspondin expired concentration (FEO2) is 0.16, the VT is 0.5 L, and the frequency of
breathing is 12. What is the VO2?
a. 0.3 L/min
b. 0.75 L/min
c. 5 L/min
d. 3.0 L/min
e. dead space volume must be known
[Fick equation applied to the respiratory system: VO2=VE * (FIO2 - FEO2)]
1.33. The partial pressure of a gas in a gaseous medium is
a. the same as its concentration
b. its fractional concentration multiplied by barometric pressure
c. depends on the solubility of the gas in the gaseous medium
d. the same as its partial pressure in a liquid (in equilibrium with the gaseous medium)
1.34. (Type A). Reduction of the pulmonary diffusing capacity to one-fourth of its normal value
would be expected to have what effect on systemic arterial oxygen pressure (PaO2) and carbon
dioxide pressures (PaCO2) of a subject resting at sea level?
a. decrease PaO2 and decrease PaCO2
b. decrease PaO2 and increase PaCO2
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312B – Practice questions– p.6
c. increase PaO2 and decrease PaCO2
d. increase PaO2 and increase PaCO2
e. decrease PaO2 but no change in PaCO2
[Comment (and answer): PaO2 decreases when DO2 decreases to less than one-third its normal value. But
DCO2 is so high normally that even a decrease to one-fourth will still permit CO2 to equilibrate in the time
that blood passes through pulmonary capillaries].
1.35. The bronchial circulation
a. is not consistently present in all subjects
b. originates from the aorta (or intercostals arteries)
c. provide venous blood to the most peripheral airways
d. provides arterial blood to the central, larger airways
1.36. In addition to gas exchange, the mammalian respiratory system can contribute to
a. production of sound
b. control of water (and heat) dissipation
c. buoyancy
d. conversion or inactivation of some substances passing through its circulation
1.37. In adult humans, the blood gas barrier
a. is about 0.2 microns in thickness
b. comprises alveolar Type 1 and Type 2 epithelial cells and capillary endothelial cells
c. has a matrix mainly made of collagen type 4 fibers
d. has cells with no nucleus
1.38. In the normal alveoli one could find
a. goblet cell
b. clara cells
c. erythrocytes
d. macrophages
1.39. The morphological model of the human trachea-bronchial tree helps to explain some
physiological phenomena, like
a. the inspired air has very small velocity when it reaches the most peripheral regions
b. the deposition of air pollutants is predominant in the bronchioli, not in the alveolar regions
c. gas diffusion, not air convection, is responsible for gas transport in the most peripheral regions
d. the airflow decreases with the increase in airway generation number
[by ‘morphological model’ one refers to the schematic representation of the tracheo-bronchial tree,
where one parent branch divides into two daughter branches, and so on until the last generation of
airways]
1.40. (Type A). During resting breathing, of the total air volume of the lung the percentage
represented by the dead space is approximately
a. 5
b. 15
c. 30
d. 50
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312B – Practice questions– p.7
e. 75
1.41. (Type A) With respect to the human lung during resting conditions, the volume of blood at
any instant in the pulmonary capillaries is about
a. 70 ml
b. 1 liter
c. 3 liters
d. approximately the same as the volume of the gas
e. approximately the same as the volume of the lung tissue
1.42. (Type A) With respect to the human lung during resting conditions, the volume of blood
per unit time in the pulmonary capillaries is about
a. 70 ml/min
b. 1 liter/min
c. 3 liters/min
d. approximately the same as alveolar ventilation
e. about half the cardiac output
1.43. Respiratory Sinus Arrhythmia
a. is a normal event in healthy subjects
b. is the increase in instantaneous heart rate during inspiration and its reduction in expiration
c. typically, decreases as the subject voluntarily increases breathing frequency
d. may be a mechanism to improve alveolar-capillary gas exchange
2.1. Generation after generation, from the central to the most peripheral airways
a. linear airflow velocity decreases
b. Reynolds' number (Re) decreases
c. total cross section increases
d. airflow decreases
2.2. The conductive airways in humans
a. have linear flow velocity higher than the airways of the respiratory zone
b. comprise approximately the first 16 generations of the tracheo-bronchial tree
c. have a smaller total cross sectional area than the airways of the respiratory zone
d. represent a large part of the anatomical dead space
2.3. In airways of generation # 3 of a normal adult man one may expect
a. the location of the equal pressure point during forced expiration
b. gas exchange
c. air linear velocity higher than in the trachea
d. the lowest concentration of pulmonary (slowly adapting) stretch receptors.
2.4. The mammalian larynx
a. decreases its airflow resistance during inspiration
b. has afferents sensitive to air temperature
c. regulates the magnitude of expiratory flow
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312B – Practice questions– p.8
d. has afferents sensitive to upper airway pressure
2.5. (Type A). In an adult subject breathing room air in Montreal (barometric pressure 760 mm
Hg) the following measurements are made:
Oxygen Consumption (VO2)
400 ml/min
Respiratory quotient (R.Q.)
0.8
Tidal volume (VT)
400 ml
Physiological Dead space (VD)
130 ml
Breathing frequency (F)
20 breaths/min
Taking into account that the alveolar pressure of water (at body temperature of 37 oC) is 47 mm
Hg, the alveolar PCO2 is close to
a.
45 mm Hg
b.
42 mm Hg
c.
40 mm Hg
d.
38 mm Hg
e.
36 mm Hg
[Application of the alveolar gas equation for CO2]
2.6. Total Lung Capacity (TLC) can be calculated from
a. inspiratory capacity (IC), expiratory reserve volume (ERV) and residual volume (RV)
b. inspiratory capacity (IC) and expiratory reserve volume (ERV)
c. vital capacity (VC) and residual volume (RV)
d. inspiratory reserve volume (IRV) and vital capacity (VC)
2.7. The spirometer can be used to measure
a.Vital Capacity (VC)
b.Functional Residual Capacity (FRC) by the Helium dilution technique
c.Oxygen Consumption, by use of a CO2 absorber on the expiratory line
d.Forced Expiratory Volume at 1 second (FEV1)
2.8. (Type A) An adult man has a dead space of 150 ml. By changing tidal volume from 500 to
1000 ml and breathing rate from 20 to 10 breaths/min his alveolar ventilation will
a. not change
b. double
c. increase by about 20%
d. decrease by about 20%
e. halve
2.9. A normal adult subject maintains the same minute ventilation of 5 liter/min with two
different breathing patterns:
(1) Tidal volume 500 ml and breathing rate 10 breaths/min
(2) Tidal volume 200 ml and breathing rate 25 breaths/min
You would expect
a. the non-elastic (i.e. airflow-resistive) work of breathing to be smaller in (1)
b. the total work of breathing greater in (2)
c. alveolar ventilation higher in (1)
d. arterial PCO2 to be higher in (1)
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312B – Practice questions– p.9
2.10. By measuring the partial pressure of carbon dioxide in the alveoli (PACO2) and in the
expired air (PECO2), one can compute
a. the physiological dead space, as long as also tidal volume is known
b. the fractional concentration of CO2 in the alveoli, as long as the barometric pressure is known
c. tidal volume, as long as the physiological dead space is known
d. the partial pressure of CO2 in the venous blood (PvCO2)
2.11. The Bohr equation
a. gives values of dead space usually smaller than the anatomical dead space
b. provides more information on the anatomical, rather than physiological dead space
c. states that tidal volume (VT) is directly proportional to the alveolar-expired CO2 difference
d. stands on the concept that the amount of CO2 collected at the mouth during expiration equals
the CO2 exchanged at the alveolar level.
2.12. In a supine man at rest, the mechanical action of the diaphragm during inspiration
a. is improved by the synchronous contraction of the intercostals inspiratory muscles
b. expands the upper rib cage
c. lowers pleural pressure
d. results in inward motion of the lower rib cage
2.13. Contraction of the diaphragm alone
a. expands the abdominal wall
b. increases pleural pressure (i.e. it makes it less sub-atmospheric)
c. expands the lower rib cage
d. expands the upper rib cage
2.14. (Type A) The expired CO2 concentration is 3% and the alveolar (or end-tidal) CO2
concentration is 5%. Tidal volume is 600 ml and breathing rate is 10 breaths/min.
Alveolar ventilation (liter/min) is
a- 2.6
b- 3.1
c- 3.6
d- 4.1
e- 2.1
[First, compute the dead space-tidal volume ratio by application of the Bohr equation. Then, calculate
alveolar ventilation from alveolar volume and breathing rate]
2.15. (Type A) While relaxed at Functional Residual Capacity (FRC), a subject connects to a bag
containing 4 liters of 10% Helium, 90% Oxygen. After re-breathing until gas mixing is complete,
the Helium concentration in the bag is found to be 5%. What is the value of FRC (in ml)?
a.
8000
b.
5000
c.
4000
d.
3200
e.
2500
[Helium does not diffuse through the alveolar-capillary membrane; therefore its quantity, which is the
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312B – Practice questions– p.10
product between gas volume and concentration, remains constant]
2.16. The static maximal inspiratory pressure is lower at FRC (Functional Residual Capacity)
than it is at RV (Residual Volume). The main reason is/are
a. force-velocity relationship of the inspiratory muscles
b. antagonistic action of the expiratory muscles at FRC
c. inward recoil of the lung (which is greater at FRC than at RV)
d. force-length relationship of the inspiratory muscles
2.17. The following statement(s) is/are correct with respect to total lung capacity (TLC)
a. TLC is limited by the combined inward recoil pressure of lung and chest wall
b. at TLC, airway resistance is less than at functional residual capacity (FRC)
c. at TLC, lung compliance is less than at FRC
d. at TLC, the maximal static inspiratory pressure during an effort against closed airways is
higher than at FRC
2.18. (Type A) The area under the velocity-force relationship of a skeletal muscle represents
a. work done by the muscle
b. energetic cost of muscle contraction
c. power done by the muscle
d. average tension produced by the muscle
e. does not have any physical meaning
2.19. The dead space
a. can be absent in respiratory systems with unidirectional gas flow
b. permits to mismatch pulmonary ventilation from alveolar ventilation
c. permits to change the breathing pattern (tidal volume and frequency) without altering alveolar
ventilation
d. influences gas exchange more at small than at large lung volumes
2.20. The area enveloped by the Lung Volume-Airway Pressure relationship constructed during
maximal static inspiratory and expiratory efforts represent
a. the total maximal work potentially performed by the respiratory muscles
b. the power of inspiratory and expiratory muscles
c. depends on the length-force characteristics of the respiratory muscles
d. depends on the velocity-force characteristics of the respiratory muscles
2.21. By modeling the human chest wall as a two-compartment model (rib cage and abdomendiaphragm)
a. the abdomen expands both during active and passive lung inflation
b. distortion occurs only during passive inflation
c. distortion occurs whenever the diaphragm contracts
d. the lower rib cage moves inward during passive inflation
2.22. (Type A) During breath-holding at total lung capacity, the operational mode of the
respiratory system is best defined as
a. active-static
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312B – Practice questions– p.11
b. active-dynamic
c. passive-static
d. passive-dynamic
e. static
2.23. In a normal subject at rest, ‘end-tidal CO2’
a. is sampled at the end of expiration
b. approximates the dead space CO2 value
c. is about 40 mm Hg
d. is close to the value of CO2 in the venous blood
2.24. If the value of alveolar CO2 is equal to that of the expired CO2
a. there is no anatomical dead space
b. there is no physiological dead space
c. alveolar ventilation (VA) equals external ventilation (VE)
d. CO2 production equals oxygen consumption
2.25. Large-size mammalian species, compared to small-size species, have
a. lower resting metabolic rate/kg (that is, per unit body weight)
b. higher respiratory system resistance (normalized by body weight)
c. lower resting pulmonary ventilation/kg
d. higher pulmonary and respiratory system compliance (per unit body weight)
2.26. (Type A) Calculation of functional residual capacity (FRC) by the Helium dilution
method.
The volume of the spirometer at the beginning and at the end of the test is 4 liters. The
concentration of Helium at the beginning and end of the test is, respectively, 1% and 0.7%. Then,
FRC is about (liters)
a. 1.7
b. 1
c. 0.7
d. 2.3
e. 4
2.27. (Type A) An adult woman is brought to the emergency room under a hysteric attack. She is
breathing at 50 breaths/min, with a tidal volume of 150 ml. The alveolar and expired
concentrations of CO2 are, respectively, 5% and 4%. The normal value of dead space ventilation
for her age and size should be 1500 ml/min. In this patient, dead space ventilation is about
a. 0.75 of the normal value
b. normal
c. twice the normal value
d. three times normal
e. four times normal
[Compute the dead space-tidal volume ratio from the Bohr equation]
2.28. (Type A) A child has a dead space of 50 ml. By increasing tidal volume from 100 to 200
ml and lowering breathing rate from 40 to 20 breaths/min his alveolar ventilation will
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312B – Practice questions– p.12
a. halve
b. not change
c. increase by about 20%
d. increase by about 50%
e. double
the lungs of adult humans, airway generations # 20-22
a. usually participate to gas exchange
b. have a total airflow (per generation) equal to that of the trachea
c. have much less smooth muscle than the trachea
d. the linear velocity of the air flow is as in the trachea
2.30. (Type A) During a normal expiration in quiet conditions the operational mode of the
respiratory system is best defined as
a. active-static
b. active-dynamic
c. passive-static
d. passive-dynamic
e. dynamic
2.31. Regarding alveolar ventilation (VA):
a. VA equals the difference between tidal volume and dead space volume.
b. VA corresponds to the ratio between CO2 production and the alveolar pressure of CO2.
c. VA is the product of tidal volume and breathing rate.
d. Subtract the volume of dead space from the tidal volume; the result multiplied by breathing
frequency is VA.
2.32. The presence of a dead space
a. raises the temperature of the inspired air nearly to body temperature.
b. saturates the inspired air with water vapor.
c. removes bacteria and other particulate matter.
d. permits to uncouple pulmonary ventilation (VE) from alveolar ventilation (VA).
2.33. Which of the following is considered INCORRECT concerning the energetics of the
respiratory muscles?
a. efficiency is defined as the ratio of mechanical work done to move air to the amount of
metabolic energy used by the respiratory muscles.
b. at rest, the respiratory system uses less than 5% of the body's total oxygen consumption
c. respiratory muscles are as efficient as large skeletal muscle groups.
d. during hyperventilation the oxygen consumption of respiratory muscles can rise up to 30% of
the total body oxygen consumption.
2.34. (Type A) Anatomical nomenclature: which of the following is the first branching of the
bronchial tree that has gas exchanging capabilities?
a. Terminal bronchioles.
b. Respiratory bronchioles.
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312B – Practice questions– p.13
c. Alveoli
d. segmental bronchi
e. alveolar ducts.
2.35. Anatomical nomenclature: Which of the following can NOT be part of a pulmonary
acinus?
a. alveolar sacs
b. Alveolar ducts
c. Respiratory bronchiole
d. Terminal bronchioles
2.36. Functional Terminology: Which of the following concerning average lung volumes and
capacities of a person at rest is TRUE? [TLC=Total Lung Capacity; VC=Vital Capacity; VT=
Tidal volume; FRC= Functional Residual Capacity; ERV= Expiratory Reserve Volume;
RV=Residual Volume; VD= Dead Space; EC=Expiratory Capacity]
a. FRC>RV>VT>VD
b. TLC>VC>VT>RV
c. TLC>VC>FRC>ERV
d. TLC>FRC>ERV>EC
2.37. (Type A) Which of the following is NOT considered a normal occurrence with increasing
age?
a. decrease of Vital Capacity.
b. increase in Residual Volume.
c. increase in Functional Residual Capacity.
d. decrease in Inspiratory Capacity.
e. increase in Expiratory Reserve Volume.
2.38. Due to polio, a patient suffers total paralysis of his chest (intercostal) muscles. For this
patient, which of the following values would still be expected to be close to normal?
a. inspiratory reserve volume (IRV)
b. expiratory reserve volume (ERV)
c. total lung capacity (TLC)
d. vital capacity (VC)
2.39. (Type A). In a child with normal lung volumes for his age (TLC = 2.5 liters, VC = 2.0
liters, ERV = 0.5 liters) the FEV1 (one-second forced expired volume) is expected to be about
a. 0.5-1.0 liters
b. 1.0-1.6 liters
c. 1.6-2.0 liters
d. 2.0-2.5 liters
e. 2.5-3.0 liters
2.40. Contraction of the abdominal muscles is important during
a. normal (quiet) inspiration
b. cough
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312B – Practice questions– p.14
c. normal (quiet) expiration
d. forced expiration
2.41. (Type A) According to the modes of operation of the respiratory system, expiration below
the resting volume of the respiratory system is
a. active and static
b. active and dynamic
c. passive and static
d. passive and dynamic
e. static and dynamic
2.42. (Type A) According to the modes of operation of the respiratory system, end-expiration
(resting volume of the respiratory system) is a condition
a. active and static
b. active and dynamic
c. passive and static
d. passive and dynamic
e. static and dynamic
2.43. (Type A) According to the modes of operation of the respiratory system, inspiration (above
the resting volume of the respiratory system) is a condition
a. active and static
b. active and dynamic
c. passive and static
d. passive and dynamic
e. static and dynamic
3.1. (Type A)
The vital capacity is the sum of
a. tidal volume and expiratory capacity
b. inspiratory capacity and functional residual capacity
c. inspiratory reserve volume, tidal volume and residual volume
d. tidal volume and inspiratory reserve volume
e. inspiratory capacity and expiratory reserve volume
3.2. (Type A)
The total lung capacity is the sum of
a. tidal volume and expiratory capacity
b. inspiratory capacity and functional residual capacity
c. inspiratory reserve volume, tidal volume and residual volume
d. tidal volume and inspiratory reserve volume
e. inspiratory capacity and expiratory reserve volume
3.3. In mammals Functional Residual Capacity (FRC)
a. decreases the amplitude of the oscillations of blood gases with tidal breathing
b. provides a reserve of oxygen
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312B – Practice questions– p.15
c. lowers the inspiratory work of breathing
d. decreases body density and favors buoyancy
3.4. Which of the following methodologies can be used to measure the breathing pattern (tidal
volume and breathing frequency)
a. spirometry
b. body plethysmography
c. chest wall motion
d. barometric technique
3.5. In a muscle-relaxed subject ventilated artificially by an external ventilator, during lung
inflation
a. alveolar pressure increases
b. pleural pressure decreases
d. rib cage expands
e. trans-chest wall pressure decreases
3.6. Lung surfactant
a. lowers surface tension
b. lowers transpulmonary pressure
c. increases alveolar stability
d. lowers chest wall compliance
3.7. If only the compliance of the chest wall decreased (i.e. lower slope of the P-V curve, as
during severe obesity), with no other alterations in the lungs or airways, one would expect
a. higher FRC (functional residual capacity)
b. lower TLC (total lung capacity)
c. increased inspiratory work of breathing during deep breathing
d. higher RV (residual volume)
[consider the P-V diagram of lung, chest wall and respiratory system]
3.8. An infant is born at 26 weeks of gestation. The lack of sufficient surfactant in his premature
lungs
a. increases the inspiratory work
b. favors expiration, by increasing lung recoil
c. decreases functional residual capacity
d. create areas of alveolar collapse (atelectasis)
3.9. A decrease in lung recoil pressure (or transpulmonary pressure)
a. occurs at low lung volumes
b. is a characteristic of patients with lung fibrosis
c. facilitates airflow limitation during a forced expiration
d. is characteristic of premature lungs with surfactant deficiency
3.10. An increase in lung recoil pressure (or transpulmonary pressure)
a. occurs at low lung volumes
b. is a characteristic of obese patients
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312B – Practice questions– p.16
c. facilitates airflow limitation during a forced expiration
d. is a characteristic of premature lungs with surfactant deficiency
3.11. (Type A) Calculation of lung compliance - A subject is breathing a tidal volume of 600 ml.
Pleural pressure at end-expiration is -3 cm H2O and at end-inspiration is -9 cm H2O.
Lung compliance (ml/cm H2O) is
a. 200
b. 100
c. 67
d. its computation requires knowledge of the transpulmonary pressure
e. its computation requires knowledge of the alveolar pressure
3.12. At Total Lung Capacity
a. the volume of the chest wall is the same as that of the lungs
b. trans-pulmonary pressure is positive
c. trans-chest wall pressure is positive
d. trans-respiratory system pressure is positive
3.13. At Residual Volume
a. the volume of the chest wall is the same as that of the lungs
b. trans-chest wall pressure is positive
c. trans-pulmonary pressure is positive
d. trans-respiratory system pressure is positive
3.14. At Functional Residual Capacity
a. the volume of the chest wall is the same as that of the lungs
b. trans-pulmonary pressure is positive
c. trans-chest wall pressure is negative
d. trans-respiratory system pressure is zero
3.15. In a fibrotic lung
a. Functional Residual Capacity is decreased
b. Lung compliance is reduced
c. Total Lung Capacity is decreased
d. Chest wall compliance is normal
3.16. A decrease in lung recoil pressure
a. occurs when lung volume decreases
b. is characteristic of patients with lung emphysema
c. facilitates airflow limitation during a forced expiratory maneuver
d. is accompanied by an increase in chest wall compliance
3.17. Surface tension is
a. present whenever an air-liquid interface is formed
b. absent in the lung of the fetus
c. very high in the lungs of a prematurely born infant
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312B – Practice questions– p.17
d. the major factor responsible for the lung recoil pressure
3.18. An infant is born prematurely at 26 weeks of gestation. You may expect
a. all subdivisions of lung volumes and capacities to be smaller than normal
b. high sensitivity to hyperoxia (oxygen therapy)
c. low lung compliance (normalized by body weight)
d. low chest wall compliance (normalized by body weight)
3.19. An increase in lung recoil pressure
a. is at Functional Residual Capacity (by comparison to Residual Volume)
b. is a characteristic of patients with lung emphysema
c. protects against airflow limitation during a forced expiratory maneuver
d. is not common in lungs with surfactant deficiency
3.20. In a liquid-filled lung
a. the lung recoil pressure is greater than in the air-filled lung
b. surface forces are as important as in the air-filled lung
c. compliance is lower than in the air-filled condition
d. lung hysteresis (i.e., the difference between the inflation and the deflation limbs of the
pressure-volume curve) is larger than in the air-filled lung
3.21. An adult man presents with left-side pneumothorax that caused atelectasis (alveolar
collapse) of one lobe of the left lung. One should expect that such patient will have
a. decreased lung compliance
b. a major (>20%) increase in airway resistance
c. decreased total lung capacity
d. increased activity of the pulmonary stretch receptors
3.22. (Type A) During a normal inspiration in resting conditions pleural pressure is
a. slightly higher (i.e. more positive) than atmospheric pressure
b. slightly higher (i.e. more positive) than alveolar pressure
c. equal to alveolar pressure
d. slightly higher (i.e. more positive) than the recoil of the chest wall
e. none of the above
3.23. In an adult healthy subject, during resting breathing in normoxia
a. the expired air has about 10% carbon dioxide
b. the expired air has more than 10% oxygen
c. oxygen consumption equals carbon dioxide production
d. alveolar ventilation is about 2/3 of minute ventilation
3.24. Lung compliance is increased
a. in emphysema
b. at high lung volume (compared to the tidal volume range)
c. in the presence of surfactants (compared to air-filled lungs without surfactants)
d. whenever lung recoil (or lung trans-pulmnonary pressure) decreases
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312B – Practice questions– p.18
3.25. Residual Volume
a. is the lowest lung volume that can be reached after maximal expiration
b. depends upon the maximal pressure generated by the expiratory muscles
c. is higher the greater the recoil pressure of the chest wall
d. is higher the greater the recoil pressure of the lungs
3.26. During maximal static expiratory efforts
a. trans-respiratory system pressure is positive
b. pleural (or esophageal) pressure is positive
c. intra-airway pressure is positive
d. trans-pulmonary pressure is positive.
3.27. In a normal healthy adult man in the standing posture, the resting position of the chest wall,
a. is somewhere around 60% of the vital capacity
b. determines its compliance
c. is a reflection of its mechanical properties
d. has major influences on the compliance of the lungs
3.28. For the same alveolar ventilation, the work of breathing increases
a. at high breathing rates
b. with high airway resistance
c. at high tidal volumes
d. with low lung compliance
3.29. High airflows in the large airways often present a turbulent regime. A decrease in
turbulence can occur in case of a drop in the
a. density of the gas
b. viscosity of the gas
c. linear velocity of the gas
d. length of the airway
3.30. A typical patient with chronic obstructive lung disease presents
a. low lung recoil
b. low “closing volume”
c. low FEV1 (Forced expiratory Volume at 1 sec)
d. low TLC (Total Lung Capacity)
[“closing volume” it the lung volume at which airways begin to close during forced expiration; it is
measured by the N2 wash-out test]
3.31. (Type A) Which of the following is NOT true concerning respiratory distress syndrome in
premature infants?
a. Their ability to synthesize dipalmitoyl phosphatidyl-choline (DPPC) is limited.
b. Higher alveolar pressures are required to ventilate the lungs.
c. Lung compliance is low.
d. Positive pressure respirators are often used to assist them in breathing.
e. Alveoli spontaneously over-expand and sometimes burst at the end of inspiration.
`
312B – Practice questions– p.19
3.32. The Reynolds' number (Re) of a gas in the airways depends on
a. the flow linear velocity
b. gas density
c. gas viscosity
d. the airway radius
3.33. The respiratory work required to inflate the lung during resting breathing is
a. inversely proportional to lung compliance
b. proportional to total pulmonary resistance
c. partly contributed by the outward recoil of the chest wall
d. progressively lower the higher the lung volume above FRC (Functional Residual Capacity)
3.34. During resting breathing
a. the work done by the inspiratory muscles corresponds to the sum of the elastic work and
airflow-resistive work
b. the elastic work is the largest component of the total respiratory work
c. the expiratory work can be entirely performed by the elastic energy stored at the end of
inspiration
d. the airflow-resistive work is usually such a small component of the total work that can be
neglected
3.35. In a supine adult man at Functional Residual Capacity (FRC) the intrapleural pressure is
a. negative (i.e., sub-atmospheric)
b. in absolute value, equal to the transpulmonary pressure
c. equal to the recoil pressure of the chest wall
d. equal to alveolar pressure
3.36. In emphysema
a. lung compliance is increased
b. lung recoil is decreased
c. total lung capacity is increased
d. functional residual capacity (FRC) is decreased
3.37. During resting breathing in an adult subject the component(s) most responsible for the
values of total respiratory resistance is (are)
a. the most peripheral airways
b. the lung tissue
c. the tissues of the rib cage
d. the large and upper airways
3.38. (Type A) As the result of a sudden increase in the airways smooth muscle tone
(“bronchomotor tone”) during an asthmatic attack, the tracheal length shortens to four/fifths (i.e.,
down to 80%) of the original length, and its diameter becomes two thirds (2/3) of the original
value. Assuming for simplicity that the airflow in the trachea was laminar, you would expect that
tracheal resistance during the attack becomes about
`
312B – Practice questions– p.20
a. 16 times higher
b. 12 times higher
c. 4 times higher
d. 2 times higher
e. 3/4 of the original value
[Poiseuille’s Law]
3.39. At FRC (Functional Residual Capacity) the static maximal expiratory pressure is lower at
than at TLC (Total Lung Capacity) mainly because
a. lower recoil of the lungs
b. greater antagonistic action of the inspiratory muscles
c. force-velocity relationship of the expiratory muscles
d. force-length relationship of the expiratory muscles
3.40. In a normal adult subject in the standing posture the resting position of the chest wall is at
about 60% of his Vital Capacity (VC). If the resting position of the chest decreased, and all other
mechanical variables (lung and chest wall compliances and resting volume of the lung) remained
the same, one should expect
a. decrease in Functional Residual Capacity (FRC)
b. the same compliance of the respiratory system
c. lower transpulmonary pressure at FRC
d. lower Residual Volume (RV)
3.41. During inflation of the lungs to the same lung volumes, the major difference(s) between a
spontaneous inspiration (i.e., active) and an artificial inflation (i.e., passive) is/are in the values
of
a. airway pressure
b. esophageal pressure
c. trans-diaphragmatic pressure
d. transpulmonary pressure
3.42. Which of the following methodologies can be used to measure the total volume of the
lungs:
a. spirometry
b. helium dilution technique
c. nitrogen washout technique
d. body box (or body plethysmograph)
3.43. Within the tracheo-bronchial tree, turbulent flow regime is more likely to occur
a. in the more central larger airways than in the peripheral smaller airways
b. while breathing a gas with low density
c. when breathing fast with high airflows
d. while breathing a high viscosity gas
[Reynolds number is proportional to (radius · density · velocity) / viscosity]
3.44. Which of the following is TRUE if a patient breathes slower than normal (half rate) with
increased tidal volume (twice normal)?
`
312B – Practice questions– p.21
a. More airflow-resistive work is done.
b. The total respiratory work done decreases.
c. Respiratory compliance is decreased.
d. More elastic work is done.
[Refer to the equation of motion of the respiratory system]
3.45. Which of the following is correct regarding FRC?
a. It is higher in the standing than in the supine posture.
b. At FRC the elastic recoil of the chest wall is outward (i.e., negative trans-chest wall pressure).
c. At FRC the elastic recoil of the lung is inward (i.e., positive trans-pulmonary pressure).
d. The relaxation pressure of the lung and chest wall combined is at atmospheric pressure.
3.46. If the lung were punctured, which of the following would happen?
a. The lung would collapse on the side of the puncture.
b. The chest wall would expand on the side of the puncture.
c. pulmonary vascular resistance of the punctured lung would increase
d. FRC would decrease
3.47. Which of the following statements is correct concerning the airflow in the lungs during
resting breathing?
a. During inspiration and expiration, the flow in the trachea and larger bronchi is turbulent.
b. Towards the middle of the bronchial tree, the flow is turbulent at the branching sites and
laminar in between.
c. Near the end of the bronchial tree, the flow is laminar.
d. The pulmonary “acinus” has very small radius; despite this, the generation of pulmonary acini
does not increase significantly the total air flow resistance of the bronchial tree.
3.48. (Type A) Which of the following represents the pressure difference that acts to distend the
lungs?
a. Alveolar pressure
b. Airway opening pressure
c. Trans-thoracic pressure
d. Trans-pulmonary pressure
e. Esophageal pressure.
3.49. A patient with low lung compliance during breathing develops the same tidal volume as a
healthy subject. Which of the following pressures is likely to be altered?
a. Pleural pressure.
b. Alveolar pressure
c. Trans-pulmonary pressure.
d. trans-chest wall pressure
3.50. (Type A) An asthma sufferer breathes at twice the normal rate. In this patient, how is the
faster breathing rate expected to affect dynamic lung compliance (Cdyn) in relation to static lung
compliance (Cstat)?
a. Cdyn remains the same as Cstat.
b. Cdyn decreases more than Cstat does.
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312B – Practice questions– p.22
c. Cdyn increases as much as Cstat does.
d. Cdyn remains the same, Cstat decreases
e. Only Cdyn decreases
[“dynamic compliance” is the compliance measured while the subject is breathing normally]
3.51. (Type A). According to the Law of Young-Laplace, air should flow from the smaller
alveoli to the larger alveoli. In the lungs, several factors counter that tendency and stabilize the
alveolar structures. Which of the following is NOT one of them?
a. Surfactant lowers surface tension to a greater degree when it is on a smaller surface area,
allowing the smaller alveoli to stay open.
b. Mechanical stability is given by surrounding alveoli, a phenomenon known as “lung
interdependence”.
c. The closure of the airways leading to the smaller alveoli helps to maintain them inflated. d.
Surface tension at the gas-liquid interface increases as alveolar surface area increases.
e. Collateral channels, which help to redirect gas from the more expanded to the less expanded
pulmonary peripheral regions
3.52. (Type A) Which of the following does NOT happen during inspiration in a normal adult
man in the standing position
a. The ribs move upward.
b. The diaphragm dome lifts up.
c. The antero-posterior dimensions of the chest are increased.
d. The tranverse dimensions of the thorax are increased.
e. The scalene and sternocleidomastoid muscles can be recruited for inspiration.
3.53. (Type A). During a normal inspiration, how does alveolar pressure compare to
atmospheric, pleural or transpulmonary pressure?
a. Alveolar pressure is greater than atmospheric.
b. Alveolar pressure equals transpulmonary.
c. Alveolar pressure is the same as atmospheric.
d. Alveolar pressure is lower (i.e., more negative) than pleural pressure
e. Alveolar pressure is higher (i.e., less negative) than pleural pressure
3.54. Alveolar surfactant acts to
a. increase surface tension
b. increase compliance
c. increase airway resistance
d. decrease the possibility of interstitial edema
[‘interstitial edema’ is accumulation of fluid in the lung interstitium]
3.55. (Type A) During resting breathing, at which of the following times in the respiratory cycle
is the intrapleural pressure most negative?
a. at the onset of inspiration
b. at the end of inspiration
c. during forced expiration
d. just before the end of expiration
e. approximately in the middle of inspiration
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312B – Practice questions– p.23
3.56. (Type A) At any given time during resting conditions in the lungs the volume of blood is
about …. the volume of air
a. one third
b. the same as
c. twice
d. about half
e. less than one fiftieth
4.1. During resting conditions in an healthy adult man the most energetically expensive
component of the breathing act is the
a. elastic work
b. airflow-resistive work
c. volume-related work
d. inertia-related work
4.2. For the same alveolar ventilation, the faster one breathes above resting values, the
a. lower the elastic work
b. higher the airflow-resistive work
c. higher the total cost of breathing
d. higher the total work of breathing
4.3. Breathing faster could increase the absolute lung volume because
a. tonic activity of the diaphragm
b. tidal volume decreases
c. laryngeal closure in expiration
d. the expiratory time is shorter than the mechanical time constant of the respiratory system
4.4. Mechanisms to elevate Functional Residual Capacity above the passive resting volume of
the respiratory system include
a. fast breathing rate
b. post-inspiratory activity of the inspiratory muscles
c. narrowing of the vocal folds during expiration
d. recruitment of extra-diaphragmatic muscles in inspiration
4.5. In a patient with chronic obstructive lung disease
a. Total Lung Capacity is increased
b. Lung recoil pressure is decreased
c. airflow limitation is increased
d. Forced Expiratory Volume in one second (FEV1) is increased
4.6. In a patient with pulmonary fibrosis
a. Total Lung Capacity is decreased
b. Lung recoil pressure is increased
c. airflow limitation is decreased
d. Functional Residual Capacity is decreased
`
312B – Practice questions– p.24
4.7. (Type A) Which of the following BEST characterizes a patient with pulmonary fibrosis?
a. Decreased Total Lung Capacity (TLC)
b. Decreased Vital Capacity (VC)
c. Decreased Functional Residual Capacity (FRC)
d. Decreased Forced Expiratory Volume at 1 sec (FEV1)
e. Increased FEV1 relative to VC
4.8. Maximal Voluntary Ventilation is
a. best reached by breathing across FRC
b. performed at high, rather than low, lung volumes
c. preferentially achieved by breathing very deep, rather than fast
d. limited by the maximal expiratory Flow-Volume curve
4.9. The effort-independent portion of the expired flow-volume curve
a. is favored by small lung volumes
b. is favored by high lung recoil pressure (or transpulmonary pressure)
c. occurs in normal subjects
d. depends on the strength of the expiratory muscles
4.10. The forced expiratory volume after 1 second (FEV1) in an adult healthy male subject
a. is about 80% of vital capacity
b. is about 4 liters
c. is reduced in emphysema
d. can be measured with a spirometer
4.11. During resting breathing, in expiration
a. the diaphragm is active throughout the whole expiratory phase
b. expiratory muscles are relaxed
c. airflow limitation is present
d. the recoil pressure of the respiratory system drives the expiratory flow
4.12. In a normal subject, Maximal Voluntary Ventilation
a. is the maximal ventilation that can be achieved
b. requires activation of the expiratory muscles
c. occurs above Functional Residual Capacity
d. involves the activation of the extra-diaphragmatic inspiratory muscles
4.13. A normal newborn infant suddenly decreases breathing frequency; the following is/are
likely to occur
a. a greater chance of pulmonary atelectasis
b. no change in the passive resting volume of the respiratory system
c. a decrease in end-expiratory level (or Functional Residual Capacity)
d. an improvement in blood gases
4.14. (Type A) – Toward the end of a normal inspiration, just before relaxation of the inspiratory
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312B – Practice questions– p.25
muscles, pleural pressure equals
a. atmospheric pressure
b. alveolar pressure
c. the recoil pressure of the chest wall
d. the negative value of the transpulmonary pressure
e. the recoil pressure of the respiratory system
4.15. (Type A) At the onset of a normal expiration, with the relaxation of the inspiratory
muscles, pleural pressure equals
a. atmospheric pressure
b. alveolar pressure
c. the recoil pressure of the chest wall
d. the negative value of transpulmonary pressure
e. the recoil pressure of the respiratory system
4.16. (Type A) At the end of a normal inspiration a subject relaxes against the occluded airways
(i.e., against mouth and nostrils closed). All the following pressures are positive (above
atmospheric), except
a. mouth pressure
b. transpulmonary pressure
c. pleural pressure
d. alveolar pressure
e. trans-respiratory system pressure
4.17. During quiet resting breathing the rate of pulmonary air flow depends on
a. alveolar pressure
b. intrapleural pressure
c. airway resistance
d. dynamic airway collapse
4.18. In normal conditions the equal pressure point
a. is located in the peripheral airways
b. moves toward the lung periphery with the decrease in lung volume
c. is more centrally located in patients with low lung recoil
d. determines the rate of expiratory flow during a forced expiration
4.19. During breathing at rest, the work done by the inspiratory muscles overcomes
a. the elastic recoil of the lung
b. the resistance to maintain pulmonary blood flow
c. airway resistance
d. the elastic recoil of the chest wall
4.20. Maximal Voluntary Ventilation is limited by the
a. maximal force of the respiratory muscles
b. water loss through the lungs
c. inspiratory flow-volume curve
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312B – Practice questions– p.26
d. expiratory flow-volume curve
4.21. An inspiration from Residual Volume (RV) to Total Lung Capacity (TLC) occurs more
rapidly than a forced expiration from TLC to RV. The reason(s) for this is/are
a. the expiratory muscles are weaker than the inspiratory muscles
b. laryngeal (glottis) narrowing in expiration
c. the outward pull of the chest wall impedes a fast expiration
d. expiratory airflow limitation
4.22. Which of the following is FALSE concerning the effect of effort on airflow and volume
during inspiration and expiration?
a. during inspiration, greater effort always results in greater flow.
b. peak expiratory flow occurs in the first half of expiration.
c. at low lung volumes, greater efforts do not result always in greater expiratory flows.
d. a portion of the expiration airflow-volume curve is effort independent.
4.23. If the equal pressure point during expiration is located in the lobar bronchi, which of the
following is TRUE?
a. Expiratory flow would be effort dependent.
b. Inspiratory flow would be effort dependent.
c. The bronchi upstream the equal pressure point (i.e., the airways located more peripherally)
would NOT cause airflow limitation.
d. The bronchi downstream the equal pressure point (i.e., the airways more centrally located)
would NOT compress.
4.24. A healthy adult subject can increase lung volume from residual volume (RV) to total lung
capacity (TLC) more quickly than he would be able to decrease it from TLC to RV, because
a. the expiratory muscles are weaker than the inspiratory muscles
b. laryngeal (glottis) narrowing in expiration
c. the outward pull of the chest wall impedes a fast expiration
d. inhibition from the slowly adapting stretch receptors
4.25. (Type A) In humans, at which of the following sites is the partial pressure of carbon
dioxide (PCO2) the lowest?
a. average exhaled gas
b. alveolar gas
c. systemic arterial blood
d. systemic venous blood
e. exhaled during the first part of expiration
4.26. (Type A) In humans, at which of the following sites is the partial pressure of carbon
dioxide (PCO2) the highest?
a. average exhaled gas
b. alveolar gas
c. systemic arterial blood
d. systemic venous blood
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312B – Practice questions– p.27
e. exhaled during the first part of expiration
4.27. (Type A). In humans, at which of the following sites is the partial pressure of oxygen (PO2)
highest?
a. exhaled gas
b. anatomical dead space at the end of expiration
c. anatomical dead space at the end of inspiration
d. alveolar gas
e. arterial blood
4.28. An individual who breathes through a hose or tube while keeping his tidal volume normal
would be expected to have increased
a. dead space
b. wasted ventilation
c. systemic arterial carbon dioxide content
d. compliance
5.1. In a subject supine, by comparison to the standing posture,
a. Functional Residual Capacity (FRC) decreases
b. Total Lung Capacity (TLC) decreases
c. Residual Volume (RV) decreases
d. Tidal Volume (VT) decreases
5.2. In large mammals, by comparison to a small mammal,
a. the pleural cavity is filled by connective tissue, rather than pleural liquid
b. the pleural pressure is at least twice more negative (more sub-atmospheric)
c. the pleural pressure swing (change in pleural pressure) during resting breathing is larger
d. the regional (e.g., top-to-bottom) unevenness in pleural pressure is twice as large
5.3. Pulmonary circulation
a. receives almost the total cardiac output
b. is a low pressure system
c. has low vascular resistance
d. increases its pressure in hypoxia
5.4. The less gravity-dependent (top) regions of the lungs, by comparison to the “gravitydependent “bottom regions,
a. receive less blood per unit time
b. receive less air ventilation per unit time
c. have greater ventilation-perfusion ratios
d. result in better oxygenated (arterialized) blood
5.5. A subject is taking a normal-size inspiration from Residual Volume (RV):
a. air will go preferentially at the top (less gravity-dependent) regions
b. blood will go preferentially at the top (less gravity-dependent) regions
c. gas exchange will be less efficient (i.e., requires more inspiratory work) than during a breath
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312B – Practice questions– p.28
from Functional Residual Capacity (FRC)
d. the average pleural pressure swing (change in pleural pressure) will be smaller than during a
breath from Functional Residual Capacity (FRC)
[here ‘efficiency’ refers to the exchange of gases for a given inspiratory work]
5.6. Factors contributing to the inequality in ventilation distribution within the lung include
a. curvilinearity of the pressure-volume curve
b. presence of surfactant
c. differences in regional pleural pressure
d. hysteresis of the tension-active function of surfactant
5.7. Factors contributing some improvement in the ventilation distribution within the lungs
include
a. lung interdependence
b. presence of surfactant
c. outward recoil pressure of the chest wall
d. short time constant of peripheral airways
5.8. “Zone 2” in the lung refers to the lung region
a. where blood flow depends on the left atrium pressure
b. where there is no blood flow
c. with small air ventilation
d. with a major blood shunt
5.9. “Zone 2” in the lung
a. refers to a lung region where blood flow depends on the arterial-alveolar pressure difference
b. is a major region of the lung
c. is the region receiving the largest portion of tidal volume
d. decreases its blood flow during forced expiration
5.10. Because of ventilation-perfusion inequalities, the alveolar-arterial oxygen pressure
difference of an adult man is 20 mm Hg (PAO2 and PaO2, respectively, 102 and 82 mm Hg).
Despite this difference tissue oxygenation remains acceptable most likely because of
a. increased cardiac output
b. higher pulmonary ventilation
c. postural adjustments
d. the shape of the hemoglobin-oxygen dissociation curve
5.11. In a patient, the right branch of the pulmonary artery is occluded and almost the whole right
lung is not blood-perfused. One should expect
a. a reduction in cardiac output
b. a decrease in the physiological dead space
c. an increase in the alveolar PCO2 of the occluded lobe
d. a reduction in arterial PO2 of the systemic blood
5.12. In a normal lung of a standing adult subject, blood flow in "zone 2" (approximately the
intermediate region) depends on
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312B – Practice questions– p.29
a. left atrial pressure
b. alveolar pressure
c. pulmonary arterial-venous pressure difference
d. pulmonary artery pressure
5.13. (Type A) In a normal lung of a standing adult subject, in "zone 1" (the uppermost region)
a. blood flow depends on left atrial pressure
b. blood flow depends on alveolar pressure
c. blood flow depends on the pulmonary arterial-venous pressure difference
d. blood flow depends on pulmonary artery pressure
e. there is no blood flow
5.14. In a normal lung of a standing adult subject, blood flow in "zone 3" (approximately the
lowermost region) depends on
a. left atrial pressure
b. alveolar pressure
c. pulmonary arterial-venous pressure difference
d. pleural pressure
5.15. In a normal subject in the sitting position, the relative distribution of the pulmonary blood
along the gravitational vector
a. depends upon breathing rate
b. depends on the depth of inspiration (tidal volume)
c. depends on cardiac output
d. is preferentially at the lower (bottom) regions
5.16. (Type A) In a normal adult subject during resting breathing a blood sample has the
following partial pressure of oxygen (PO2) and partial pressure of carbon dioxide (PCO2)
PO2
=
95 mm Hg
PCO2
=
43 mm Hg
This sample is likely to
a. originate from the arterial capillaries at the top lung regions
b. originate from the arterial capillaries at the bottom lung regions
c. originate from the arterial capillaries at the middle portions of the lung
d. represent "shunted blood" which bypassed the gas-exchange area
e. represent mixed venous blood
[remember that the “average” arterial PO2 and PCO2 is, respectively,100 and 40 mm Hg]
5.17. (Type A) - In a normal adult subject during resting breathing a sample of blood has the
following partial pressure of oxygen (PO2) and partial pressure of carbon dioxide (PCO2)
PO2
=
40 mm Hg
PCO2
=
47 mm Hg
This blood sample is likely to originate from the
a. left ventricle
b. arterial capillaries at the lower regions of the lung (“gravity dependent” lung regions)
c. arterial capillaries at the middle portions of the lung
d. descending aorta
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312B – Practice questions– p.30
e. right ventricle
5.18. Differences in ventilation distribution among lung regions are more marked the greater the
a. curvilinearity of the pressure-volume curve
b. action of surfactant
c. pleural pressure gradient
d. lung interdependence
5.19. (Type A) - Which of the following associations BEST describes the cause of the nonuniform ventilation distribution in the lungs:
a. curvilinear pressure-volume curve of the lungs AND uneven airways resistance
b. pleural pressure gradient AND regional differences in time constants
c. pleural pressure gradient AND regional differences in chest wall compliance
d. pleural pressure gradient AND curvilinear pressure-volume curve of the lungs
e. curvilinear pressure-volume curve of the lung AND gradual recruitment of the inspiratory
muscles
5.20. The non-uniform ventilation distribution in the lung
a. depends on the absolute lung volume at which inspiration begins
b. is present in all body postures
c. depends on the shape of the lung pressure-volume curve
d. depends on the pleural pressure gradient
5.21. In a supine subject breathing quietly from FRC (Functional Residual Capacity) most of the
inspired air is directed to the posterior (vertebral) regions because
a. their airflow resistance is low
b. these regions have more surfactant
c. the regional transpulmonary pressure of these regions is higher than in the sternal regions
d. at FRC the posterior regions are more compliant than the sternal regions
5.22. When a subject is holding his breath at Residual Volume (RV)
a. the airways at the bottom of the lung are likely to be collapsed
b. alveolar pressure is equal to atmospheric pressure
c. the chest wall tends to expand
d. transpulmonary pressure is positive
5.23. (Type A). In an adult man cardiac output is 5 liters/min, mean pulmonary artery pressure is
17 cm H2O and wedge (left atrial) pressure is 2 cm H2O; hence, total pulmonary vascular
resistance (cmH2O·l-1·min) is
a. about 3
b. about 0.33
c. impossible to compute without knowing alveolar pressure
d. impossible to compute without knowing the lung zone (1, 2 or 3)
e. impossible to compute without knowing the posture of the patient (i.e., the gravitational field)
5.24. (Type A) A patient with otherwise normal lungs has a right-to-left shunt. At
catheterization, the oxygen concentration in his arterial and mixed venous blood is 18 and 14 ml
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312B – Practice questions– p.31
·100 ml−1, respectively. If the O2 concentration of the blood leaving the pulmonary capillaries is
calculated to be 20 ml · 100 ml−1, what is his shunt as a percentage of his cardiac output?
a. 23
b. 33
c. 43
d. 53
e. 63
[This question is about the shunt equation, where the shunt as fraction of cardiac output is (pulmonary
capillary-arterial content) / (pulmonary capillary-venous content)].
5.25. The apex of the upright human lung by comparison to its base has
a. higher Po2.
b. higher ventilation
c. higher pH in end-capillary blood
d. smaller alveoli.
[the question refers to the distribution of pulmonary ventilation, perfusion, and their ratio]
5.26. Which of the following applies to the alveoli at the base of the lungs?
a. during inspiration from FRC they undergo a larger volume change than the alveoli at the apex.
b. their regional pleural pressure is lower (i.e., less subatmospheric).
c. at FRC they are less inflated than the alveoli at the apex.
d. their absolute volume is smaller than that of the alveoli at the apex.
5.27. Which of the following is TRUE concerning the “closing volume” for the lung?
a. originates between “Phase 3” and “Phase 4” of the single breath N2 washout.
b. marks the volume where the alveoli at the bottom of the lung close during expiration.
c. marks a sudden increase in nitrogen concentration in the expelled breath.
d. marks the lung volume at which the lesser ventilated alveoli of the apex deflate air with high
N2 concentration.
[‘closing volume’ is the lung volume at which airways begin to close during expiration. It is determined
by monitoring N2 at the mouth during expiration immediately after a full inspiration of pure O2; this is
known in pulmonary function testing as the ‘N2 washout test’)
5.28. (Type A) When is the resistance to blood flow of the pulmonary vascular bed lowest?
a. When a person is at rest sitting up
b. When a person is at rest lying down
c. When a person is breathing air at high altitude
d. When a person is exercising maximally
e. None of the above because pulmonary vascular resistance is constant
[Consider the role of absolute lung volume on the pulmonary vasculature (through changes in vessel
diameter and capillary recruitment) and the effect of hypoxia on pulmonary vascular resistance]
5.29. Which of the following might be expected to lead to pulmonary edema?
a. decrease pulmonary arterial pressure (pulmonary hypotension)
b. very high negative alveolar pressures (as during snorkeling at depth)
c. increase systemic venous pressure (as in right heart failure)
d. increase pulmonary capillary permeability to plasma proteins (as in pulmonary inflammation)
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312B – Practice questions– p.32
[Consider that the blood osmotic pressure keeps fluid from leaving the pulmonary capillaries and
prevents fluid accumulation into the interstitial space and alveoli]
5.30. (Type A) In a person standing upright, which region of the lungs has the highest ventilation
rate and which region has the highest circulatory perfusion rate?
a. highest ventilation: Apex; highest perfusion: Apex
b. highest ventilation: Apex; highest perfusion: Base
c. highest ventilation: Base; highest perfusion: Apex
d. highest ventilation: Base; highest perfusion: Base
e. there is no "highest" region as the apex and base have equal ventilation and perfusion rates
6.1. The time required to exhale during expiration is prolonged by
a. narrowing of the glottis
b. increased lung compliance
c. an increase in airways resistance
d. an increase in lung recoil pressure
6.2. Tidal inspiration during resting breathing in a standing normal adult subject is associated
with the following event(s)
a. decrease in alveolar pressure
b. increase in transpulmonary pressure
c. outward and upward movement of the lower rib cage
d. increase in abdominal pressure
6.3. Breathing frequency most commonly
a. decreases with the decrease in animal size
b. is higher in aquatic, than in terrestrial, mammals of similar size
c. is lower in newborns than in adults
d. increases after bilateral section of the vagi nerves
6.4. The central breathing pattern generator
a. is believed to comprise a network of nuclei
b. is thought to be kept in check by structures in the pons
c. is likely to be controlled by metabolic stimuli
d. receives inputs from the vagal afferents
6.5. For a given output of the respiratory central pattern generator, the magnitude of pulmonary
ventilation depends on
a. body temperature
b. magnitude of dead space
c. blood gases
d. mechanical properties of the respiratory system
6.6. An abnormal reduction of the ventilatory response to hypoxia could be due to
a. decreased sensitivity of the carotid body
b. anesthesia
c. depression of the central pattern generator
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312B – Practice questions– p.33
d. decreased compliance of the respiratory system
6.7. Breathing “across” Functional Residual Capacity (FRC) instead of breathing “above” it
a. decreases the elastic (volume-dependent) work of breathing
b. favors closure of the lower-most regions of the lungs
c. is uncommon in mammals
d. requires activation of the expiratory muscles
6.8. Pulmonary stretch receptors
a. get stimulated by changes in airway tension
b. are located mainly in the most peripheral airways of the lung
c. mediate the Hering-Breuer inflation reflex
d. are sensitive to small changes in air temperature
6.9. Pulmonary slowly adapting "stretch" receptors increase their activity when
a. lung volume increases
b. transpulmonary pressure increases
c. end-expiratory volume increases
d. airway tension (or “bronchomotor tone”) increases
6.10. Pulmonary stretch receptors
a. send information related to lung volume, although their proper stimulus is airway tension
b. are mostly active in inspiration, but some are active throughout the whole breathing cycle
c. inhibit inspiratory activity
d. mediate the “Head's paradoxical reflex”
[the “Head’s paradoxical reflex” is an brief inspiratory activity that closely follows a rapid lung
inflation]
6.11. The spontaneous deep breath (or “sigh”)
a. originates from the activation of pulmonary rapidly adapting “irritant” receptors
b. occurs mostly in conditions of high airway resistance
c. originates periodically when lung compliance decreases
d. occurs more frequently when breathing at high lung volumes
6.12. Pulmonary 'J' receptors
a. are located in the interstitial space of the pulmonary tissue
b. are stimulated by lung congestion
c. once activated, cause rapid and shallow breathing pattern
d. send information to the respiratory centers via unmyelinated small diameter fibers
6.13. (Type A) Section of the brainstem at the level of the midpons most likely results in
a. cough
b. long apneas
c. activation of the expiratory muscles
d. slow and deep respiration
e. is incompatible with survival
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312B – Practice questions– p.34
6.14. The pulmonary rapidly adapting "irritant" receptors are
a. part of a protective neural mechanism
b. the afferent component of the “Head's paradoxical reflex”
c. mostly located in large and central airways
d. primarily inhibiting inspiratory activity
6.15. After bilateral section of the pulmonary vagal afferents
a. tidal volume increases
b. total pulmonary resistance decreases
c. breathing frequency decreases
d. spontaneous deep breaths (sighs) are abolished
6.16. The Hering-Breuer inflation reflex
a. consists in the inhibition of inspiratory activity as lung volume increases
b. is mediated by the activation of the rapidly adapting “irritant” receptors
c. promotes expiratory activity as lung volume is kept elevated
d. is absent in infants
6.17. In a sleeping newborn infant the airways suddenly get totally obstructed at end-expiration.
The following respiratory effort against such occlusion
a. lasts longer than the normal (open-airways) inspiratory time
b. produces a larger than normal change in transpulmonary pressure
c. produces a larger than normal decrease in pleural pressure
d. is limited in duration by the strength of the infant's inspiratory muscles
6.18. During resting breathing in expiration
a. the expiratory muscles are inactive
b. the recoil of the chest wall contributes to expiratory flow
c. surface tension contributes to expiratory flow
d. expiratory flow limitation influences the duration of expiration
6.19. An OSA (Obstructive Sleep Apnea) patient is asleep. Accidentally, his airways get totally
occluded; without waking up, the patient makes an inspiratory effort against the occlusion. The
airway pressure developed during such effort is greater than the pleural pressure swing during
normal (open airways) inspiration, most likely because
a. the diaphragm is maintaining its length (Force-Length relationship)
b. the diaphragm velocity of shortening is close to nil (Force-Velocity relationship)
c. the pulmonary slowly adapting stretch receptors do not increase their end-expiratory activity
d. the hypoxic stimulus accompanying the obstruction
6.20. The breath-by-breath stability of the breathing pattern against respiratory loads (e.g., in
cases of a sudden decrease in pulmonary compliance or increase in airway resistance) is provided
by
a. the intrinsic mechanical properties of the respiratory muscles (force-length and force velocity
relationships)
b. periodic activation of the rapidly adapting “irritant” receptors
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312B – Practice questions– p.35
c. vagal feed-back mechanisms mediated by the pulmonary slowly adapting stretch receptors
d. carotid chemoreceptors
6.21. When changing posture from the standing to the supine (horizontal, belly up) position
a. functional residual capacity (FRC) decreases
b. the inspiratory mechanical efficiency of the diaphragm increases
c. peripheral airway resistance increases
d. the within-breath oscillations in blood gases increase
6.22. Which of the following pairs is correct regarding pulmonary mechanoreceptor and their
stimulus?
a. Lung slowly adapting (stretch) receptors: tension in the airways wall
b. Lung rapidly adapting (irritant) receptors: decrease in lung compliance
c. Juxta-capillary receptors: tension in the interstitial space of the alveolar-capillary membrane.
d. Lung rapidly adapting (irritant) receptors: dust in the airways
6.23. Which of the following pairs is correct regarding pulmonary mechanoreceptor and their
reflex response?
a. Lung slowly adapting (stretch) receptors: inhibition of inspiratory activity
b. Lung rapidly adapting (irritant) receptors: facilitation of inspiratory activity
c. Juxta-capillary receptors: rapid and shallow breathing
d. Lung slowly adapting (stretch) receptors: facilitation of expiratory activity
6.24. (Type A). Which of the following pairs of central nervous system regions and input or
conditions is INCORRECT concerning their ability to influence respiration?
a. Cerebellum: muscle mechanoreceptor input
b. Limbic system: emotional states
c. Cerebral cortex: voluntary control
d. Cerebral motor cortex: muscle exercise
e. Nucleus of the solitary tract: lung mechanoreceptor
6.25. (Type A) A vascular stroke that destroyed the respiratory center of the medulla would be
expected to lead to
a. immediate cessation of breathing
b. apneustic breathing
c. brief periods of apnea
d. rapid breathing (hyperpnea)
e. abolition of sighs (deep breaths)
6.26. (Type A) The afferent (sensory) endings for the Hering-Breuer reflex are stretch receptors
(mechanoreceptors) in the
a. aorta and carotid arteries
b. arteries in the cerebral circulation
c. lungs
d. heart
e. diaphragm and intercostal muscles
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312B – Practice questions– p.36
6.27. (Type A) Before a breath-hold, hyperventilation allows one to hold his breath for a longer
period of time because hyperventilation
a. increases the oxygen reserve of systemic arterial blood
b. decreases the PCO2 of systemic arterial blood
c. decreases the pH of systemic arterial blood
d. increases brain blood flow
e. increases the level of consciousness, which favors the voluntary breath-holding
7.1. Diffusion time of oxygen for the saturation of the hemoglobin in a pulmonary capillary of a
normal lung at sea level
a. is about 0.25 sec
b. increases when the venous O2 pressure is high
c. decreases when breathing pure O2
d. decreases in conditions of interstitial edema
7.2. A leftward shift of the oxygen-hemoglobin dissociation curve is expected
a. during exercise
b. with a decrease in temperature
c. with a decrease in pH
d. with a decrease in blood PCO2
7.3. The reactions that allow red cells to load CO2 at the tissue level
a. result in a movement of HCO3- from plasma to the red cells
b. are possible because of the carbonic anhydrase in plasma
c. result in movement of Cl- from the red cells to plasma
d. result in some degree of blood alkalosis
7.4. In the blood, carbonic anhydrase
a. is found mostly in the plasma compartment
b. increases the speed of dissociation of H2CO3 into HCO3- and H+
c. favors the loading of CO2 on the hemoglobin
d. favors the interaction between CO2 and proteins
7.5. The quantity of O2 loaded by the blood at the pulmonary level
a. approximately doubles when breathing pure O2
b. usually is incomplete during exercise
c. requires about 1 sec during resting conditions
d. is determined by the O2 pressure gradient between alveoli and mixed venous blood
7.6. (Type A) CO2 is carried in the blood mostly in the form of
a. bicarbonate (HCO3-) in the plasma
b. HCO3- in the red cells
c. physically dissolved in plasma
d. carbamino compounds with plasma proteins
e. bound to haemoglobin
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312B – Practice questions– p.37
7.7. The entrance of Cl- into the red cell (“chloride shift”)
a. occurs during the process of gas exchange at the tissue level
b. depends upon the amount of hemoglobin available
c. is related to the outward movement of HCO3d. increase during hyperoxia
7.8. The total pressure of the gases in the venous blood is less than in the arterial blood. The
factor(s) responsible for this venous-arterial difference is/are
a. Bohr effect
b. higher affinity of hemoglobin for CO2 than for O2
c. lower blood pressure in the veins than in the artery
d. different shapes of the [O2]-PO2 and the [CO2]-PCO2 curves
(d)
7.9. Carbon monoxide (CO) is a very dangerous gas to inhale. This is because CO
a. has an extremely high affinity for hemoglobin
b. causes pulmonary edema
c. does not stimulate the carotid body
d. has a misleadingly pleasant odor
7.10. The partial pressure of oxygen (PO2) at 50% of hemoglobin-O2 saturation (P50)
a. decreases with an increase in temperature
b. increases with the increase in carbon dioxide partial pressure (PCO2)
c. decreases in acidosis
d. usually is higher in mammals of smaller size (than in mammals of larger size)
[comment: in small size mammals with high metabolic activity a low O2-affinity may be advantageous to
facilitate the unloading of oxygen in the tissue capillaries]
7.11. The affinity of hemoglobin for oxygen decreases
a. with a decrease in red cell 2,3 DPG
b. when body temperature decreases
c. with blood alkalosis
d. during prolonged muscle exercise
7.12. (Type A) The affinity of the hemoglobin (Hb) for oxygen is a concept that is numerically
expressed by the
a. Hb saturation in the arterial blood
b. partial pressure of oxygen when Hb is 50% O2-saturatted
c. the effect of hyperoxia on the partial pressure of oxygen in the arterial blood (PaO2)
d. effect of CO2 on the Hb-PaO2 curve
e. the slope of the PaO2-Hb saturation curve
7.13. (Type A) A 55 year-old patient is breathing rapid and shallow. His arterial partial pressure
of oxygen (PaO2) is 73 mm Hg. After 15 min of breathing 70% O2, PaO2 is 74 mm Hg.
Which of the following is the most likely explanation for the minimal change in PaO2 ?
a. the small alveolar ventilation
b. low lung compliance
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312B – Practice questions– p.38
c. high pulmonary resistance
d. pulmonary vascular shunt
e. anemia
7.14. (Type A) If a climber on the summit of Mt. Everest (barometric pressure 247 mm Hg)
maintains an alveolar PO2 of 34 mm Hg and is in a steady state (Respiratory Exchange Ratio
RER ≤ 1), his alveolar Pco2 (in mm Hg) cannot be any higher than
a. 4
b. 8
c. 10
d. 12
e. 15
[By application of the alveolar gas equation for O2, PAO2= PIO2-PACO2/RER. The inspired Po2 = 0.21
× (247 − 47) or 42 mm Hg. Therefore, from this alveolar gas equation, the alveolar Po2 is 42 −
Pco2/RER, where RER is equal to or less than 1. Hence, to maintain an alveolar Po2 of 34 mm Hg, the
alveolar Pco2 cannot exceed 8 mmHg]
7.15. (Type A) If the ventilation-perfusion ratio of a lung unit is decreased by partial bronchial
obstruction while the rest of the lung is unaltered, the affected lung unit will show
a. increased alveolar Po2
b. decreased alveolar Pco2.
c. no change in alveolar PN2.
d. a rise in pH of end-capillary blood.
e. a fall in oxygen uptake.
[Consider that N2 is inert, but its concentration depends on what happens to the other respiratory gases]
7.16. (Type A) A patient with lung disease who is breathing air has an arterial Po2 and Pco2 of 49
and 48 mm Hg, respectively, and a respiratory exchange ratio (RER) of 0.8. The approximate
alveolar-arterial difference for Po2 (in mm Hg) is
a. 10
b. 20
c. 30
d. 40
e. 50
[First, calculate the ‘ideal’ alveolar Po2 using the alveolar gas equation for O2 (PAO2 = PIO2 – PACO2 /
RER), keeping in mind that alveolar and arterial PCO2 are essentially equal]
7.17. (Type A) A climber reaches an altitude of 4,500 m (14,800 ft) where the barometric
pressure is 447 mm Hg. The Po2 of the inspired gas (in mm Hg) is about
a. 47
b. 63
c. 75
d. 84
e. 90
[the water vapor pressure in the body depends solely on body temperature]
7.18. (Type A) A man with normal lungs and an arterial Pco2 of 40 mm Hg takes an overdose of
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312B – Practice questions– p.39
barbiturate. The effect of the overdose is to half his alveolar ventilation with no change in CO2
output. If his respiratory exchange ratio is 0.8, what will be his arterial Po2 (in mm Hg),
approximately?
a. 40
b. 50
c. 60
d. 70
e. 80
[First, compute the alveolar PCO2 by application of the alveolar gas equation for CO2. Then, plug the
result into the alveolar gas equation for O2]
7.19. (Type A) In the situation described in the previous question, how much does the inspired
O2 concentration (%) have to be raised to return the arterial Po2 to its original level?
a.7
b.11
c.15
d.19
e.23
[comment: this example emphasizes how powerful the effect of increasing the inspired oxygen
concentration on the arterial Po2 is when hypoxemia is caused by hypoventilation]
7.20. (Type A) If a patient's blood carries 10 grams of Hb per deciliter, what is the approximate
O2 carrying capacity of his blood (in ml/deciliter) at 50% Hb saturation?
a. 6
b. 9
c. 11
d. 13
e. 15
[Consider that 1 g Hb at full saturation carries 1.24 mlO2]
7.21. Which of the following definitions is/are CORRECT?
a. O2 content of blood is the actual amount of O2 in one deciliter of blood.
b. O2 saturation of blood is the ratio of O2 content to its O2 capacity.
c. The O2 uptake curve of blood is the functional relationship between O2 content and its partial
pressure PO2 (Y and X axis, respectively)
d. The O2 content of blood depends entirely on the amount of Hb in the blood.
7.22. Which of the following statements about hemoglobin (Hb) is/are CORRECT?
a. A higher P50 than normal means that O2 binds less tightly to Hb.
b. An increase in 2,3-DPG shifts the O2 uptake curve to the left.
c. An increase in carbon dioxide pressure (PCO2) causes a right shift of the O2 uptake curve.
d. A decrease in pH decreases P50.
7.23. Which of the following forms of CO2 can be transported in the blood?
a. Bicarbonate
d. Dissolved in the blood.
c. Bound to the amino end groups in proteins.
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312B – Practice questions– p.40
d. Bound to the imidazole ring of glutamate.
7.24. Which of the following is/are FALSE concerning CO2 uptake?
a. If blood PO2 equals blood PCO2, then there will be more total CO2 in the blood.
b. Oxygenation moves the CO2 uptake curve downward.
c. The CO2 uptake curve is generated by comparing the blood PCO2 with total CO2 per unit
volume of blood.
d. Deoxygenated blood carries less CO2 than oxygenated.
[‘CO2 uptake curve’ is another way of saying ‘PCO2-CO2 content relationship’]
7.25. If you blocked the blood supply to a lobe, which of the following would occur in that lung
region and systemically as a result?
a. The ventilation perfusion ratio of the region would be 0.
b. The alveolar oxygen pressure (PAO2) of the region would be greater than normal.
c. The alveolar carbon dioxide pressure (PACO2) of the region would approach the venous value.
d. systemic arterial blood would have a lower oxygen partial pressure (PaO2)
7.26. Which of the following is/are CORRECT concerning the ventilation and perfusion of
different regions of the lung?
a. Alveoli at the top of the lung have a smaller dynamic compliance.
b. The hemoglobin (Hb) flowing through the base of the lung is less saturated than that at the
apex of the lung.
c. Alveolar oxygen pressure (PAO2) at the apex of the lung is higher than that at the base of the
lung.
d. In normal adult lungs, variations of the ventilation/perfusion ratio among lung regions are less
than 5%.
7.27. (Type A) Calculate the alveolar oxygen pressure (PAO2) for a person at sea level with a
Respiratory Exchange Ratio (RER) = 0.82 and alveolar CO2 (PACO2) = 40 torr.
a. 110 Torr.
b. 95 Torr
c. 80 Torr
d. 101 Torr
e. 150 torr
[application of the alveolar gas equation for O2]
7.28. To which of the following is alveolar PCO2 directly proportional?
a. Pulmonary ventilation
b. Rate of O2 consumption.
c. Alveolar ventilation
d. Rate of CO2 production
7.29. In what situation would the respiratory gas exchange ratio (RER) be increased compared to
the respiratory quotient (RQ)?
a. At the onset of a run
b. During sudden hyperventilation.
c. During acute hypoxia.
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312B – Practice questions– p.41
d. During breath-holding.
[Consider the implications of the CO2 stores on RER]
7.30. (Type A) At an altitude of 5,500m (barometric pressure 380mmHg), if the alveolar CO2
pressure (PACO2) was 40 mmHg and the respiratory exchange ratio (RER) was 0.8, the oxygen
alveolar pressure (PAO2) will be:
a. 20mmHg
b. 30mmHg
c. 40mmHg
d. 50mmHg
e. 60mmHg
[alveolar gas equation for O2: PAO2= [(FIO2 * (Pb – Pwater)) – PACO2 / RER]
7.31. (Type A) Blood gas measurements in a hypoxic patient indicate that the patient’s systemic
arterial oxygen content is normal but his systemic venous oxygen content is low. This is
characteristic of
a. diffusion limitation
b. right-to-left shunt
c. pulmonary ventilation/perfusion non-uniformity
d. anemic hypoxia (low Hb concentration)
e. stagnant hypoxia (low cardiac output)
[High oxygen extraction (large difference between arterial and venous O2 content) is characteristic of
inadequate tissue blood flow].
7.32 (Type A) A patient has a normal oxygen partial pressure and content in pulmonary venous
blood but his systemic arterial blood shows a significantly lower than normal oxygen partial
pressure and content. The single most likely possibility is
a. diffusion limitation
b. pulmonary ventilation/perfusion non-uniformity
c. stagnant hypoxia (low cardiac output)
d. right-to-left shunt
e. severe anemia
[consider that in the arterial blood, before O2 content decreases significantly, the partial pressure of O2
must decrease substantially (<75 mm Hg)]
7.33 (Type A) Which of the following best describes the correct path of CO2 from the tissue to
the atmosphere?
a. Reaction with H2O to make H2CO3, dissociation to H+ and HCO3-, H+ combines with
imidazole side chain of hemoglobin, carried back to lungs as HHb+ and HCO3- in the plasma,
reverse reaction forms CO2.
b. O2 is metabolized to CO2, reaction with H2O to make H2CO3, H2CO3 combines with imidazole
side chain of hemoglobin, H2CO3Hb+ is carried back to the lungs, reverse reaction forms CO2.
c. Reaction with H2O to make H2CO3, dissociation to H+ and HCO3-, HCO3- combines with
imidazole side chain of hemoglobin, carried back to the lungs as HCO3-Hb+ and H+, reverse
reaction forms CO2.
d. O2 is metabolized to CO2, reaction with H2O to make H2CO3, dissociation to H+ and HCO3-,
carried back to lungs in these two forms in the red cells, reverse reaction forms CO2.
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312B – Practice questions– p.42
e. Reaction with H2O to make H2CO3. The rise in bicarbonate is offset by a rise in CO2 to
maintain pH constant. Then in the lungs, CO2 is eliminated and HCO3- drops.
7.34. (Type A). As blood passes through systemic capillaries, the enzyme carbonic anhydrase
catalyzes
a. conversion of dissolved CO2 to carbonic acid
b. conversion of carbonic acid to bicarbonate ion
c. conversion of gaseous CO2 to dissolved CO2
d. binding of carbon dioxide to hemoglobin, thus displacing oxygen
e. facilitates the diffusion of CO2 from cells into blood
[Carbonic anhydrase catalyzes the reaction CO2 + H2O <=> H2CO3]
7.35. (Type A). What would be the expected systemic arterial oxygen content of a normal person
inhaling pure oxygen (100% O2) for an hour or so?
a. 100 ml O2 / dl blood (100 ml blood)
b. 40 ml O2 / dl blood (100 ml blood)
c. 22 ml O2 / dl blood (100 ml blood)
d. 11 ml O2 / dl blood (100 ml blood)
e. none of the above, since pure oxygen is highly toxic
[Consider that Hb is almost entirely saturated at PaO2=100 mm Hg. It requires several hours of
breathing pure O2 to induce lung oxygen toxicity.]
7.36. (Type A) An oxyhemoglobin saturation of mixed systemic venous blood of 25% for a
person at rest is
a. above normal
b. below normal
c. within the normal range at any age
d. normal for women, not for men
e. normal only for elderly persons
[Consider the PO2-HbO2 curve, and that the venous PO2 is about 46 mm Hg]
7.37. (Type A) As blood passes through systemic capillaries, what happens to the affinity of
hemoglobin for oxygen and what happens to the Hb-O2 dissociation curve?
a. Hb affinity for O2 increases and the dissociation curves shifts to the left
b. Hb affinity for O2 increases and the dissociation curves shifts to the right
c. Hb affinity for O2 decreases and the dissociation curves shifts to the left
d. Hb affinity for O2 decreases and the dissociation curves shifts to the right
e. neither Hb affinity for O2 nor the Hb-O2 dissociation curve change
7.38. (Type A) A hemoglobin concentration in systemic venous blood of 20 gm/dl blood is
a. above normal (as in polycythemic patients)
b. below normal (as in anemic patients)
c. within the normal range
d. normal for women, not for men
e. normal only for elderly persons
[Comment/answer: Normal hemoglobin concentration in young adult men and women is,
respectively, 16 and 14 gm/dl. Thus, a value of 20 gm/dl is significantly above normal; this
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312B – Practice questions– p.43
person would be classified as polycythemic].
7.39. (Type A). What would be the expected effect of pulmonary edema on the pulmonary
diffusing capacity for oxygen (DO2) and carbon dioxide (DCO2)
a. reduce DO2 and reduce DCO2
b. reduce DO2 but no effect on DCO2
c. reduce DCO2 but no effect on DO2
d. no effect on either DO2 or DCO2
e. no effect on either DO2 or DCO2 unless diffusing area is reduced also
[Comment/answer: Of course, both DO2 and DCO2 would be reduced. Note, however, that the diffusing
capacity decrease has a greater effect on blood oxygen than on blood carbon dioxide because DCO2 is
normally so much higher than DO2]
7.40. The following system(s) act(s) as “buffer” for hydrogen ions in the blood
a. Hemoglobin
b. Bicarbonate
c. Phosphate
d. Calcium sulphate
7.41. (Type A). In an adult man, arterial PCO2 is 30 mm Hg, pH 7.35, bicarbonate is 15 mEq/l.
The best definition of this situation is
a. respiratory acidosis
b. respiratory alkalosis
c. metabolic acidosis partially compensated
d. metabolic and respiratory acidosis combined
e. metabolic alkalosis
7.42. In humans, which of the following sites has the highest partial pressure of carbon dioxide
(PCO2)?
a. exhaled gas
b. alveolar gas
c. systemic arterial blood
d. systemic venous blood
8.1. (Type A) “Hyperventilation” means that
a. alveolar ventilation exceeds its normal level
b. pulmonary ventilation exceeds its normal level
c. breathing frequency is above normal
d. the inspiratory muscles are more active than in resting conditions
e. the alveolar partial pressure of CO2 (PACO2) is decreased
8.2. In adult humans, core body temperature
a. is approximately constant (within 1ºC) over the thermoneutral range
b. oscillates slightly (0.5-1ºC) throughout the 24-hours
c. results from the balance between heat production and heat loss
d. decreases as ambient temperature drops below thermoneutrality
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312B – Practice questions– p.44
8.3. During resting normoxic conditions, thermoneutrality is the range in ambient temperature
a. where oxygen consumption is minimal
b. where body temperature is controlled by heat production mechanisms
c. where heat dissipation mechanisms control body temperature
d. that corresponds to the subject’s preferred temperature
8.4. (Type A)- Which of the following statements BEST defines “thermoneutrality” ?
a. range in body temperature with minimal oxygen consumption (VO2)
b. range in ambient temperature where thermogenesis controls body temperature
c. range in ambient temperature where most mammals feel comfortable
d. range in ambient temperature where body temperature is maintained with minimal VO2
e. range in ambient temperature where heat dissipation mechanisms are operational
8.5. The physical process(es) in the regulation of heat loss is (are)
a. evaporation
b. convection
c. radiation
d. diffusion
8.6. Heat loss by evaporation can occur through
a. pulmonary ventilation
b. sweating
c. “perspiratio insensibilis”
d. spreading of saliva on pelt and skin
[perspiratio insensibilis is a Latin term to define a physiological process of continuous and almost
undetectable loss of water from skin, mucosas and airways]
8.7. An adult man is sunbathing in a hot environment (41.4°C). His body temperature is currently
37.8°C and rising. In this condition, the mechanism(s) to lose heat and avoid heat stroke is/are
a. behavioral (move away toward a cool environment)
b. stay and activate heat loss by radiation
c. stay and activate heat loss by evaporation
d. stay and activate heat loss by conduction
8.8. During resting conditions at the higher critical temperature of thermoneutrality
a. heat loss is minimal
b. oxygen consumption is the same as carbon dioxide production
c. evaporation is the only mechanism of heat loss
d. body temperature is normal
8.9. Body temperature
a. among adult mammals, varies according to body size
b. oscillates according to circadian patterns
c. is regulated by cortical regions of the neocortex
d. when increased, stimulates breathing frequency
8.10. The ‘sphere analogy’ applied to mammalian bodies implies that small animals (by
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312B – Practice questions– p.45
comparison to large body-size animals)
a. have a larger mass-specific surface area
b. loose heat more easily (per unit of body weight)
c. gain heat more easily (per unit of body weight)
d. have higher body temperature
8.11. The ‘sphere analogy’ applied to mammalian bodies implies that small animals (by
comparison to large body-size animals) must have
a. greater evaporative heat loss (per unit of body weight)
b. lower oxygen consumption (per unit of body weight)
c. greater skin radiation (per unit of body weight)
d. smaller circadian oscillations in body temperature
8.12. At the ambient temperature of 39°C and 100% relative humidity, the prevalent
mechanism(s) of heat loss for a normal adult human is (are)
a. evaporation
b. conduction
c. convection
d. radiation
8.13. In a condition of equilibrium at rest (“resting steady state”), one or more of the following
can be taken as index of whole-body metabolic activity
a. heat production
b. carbon dioxide production
c. oxygen consumption
d. food intake
8.14. In condition of equilibrium (“steady state”) the respiratory quotient (RQ)
a. is equivalent to the Respiratory Exchange Ratio
b. is the ratio between oxygen consumption and carbon dioxide production
c. is between 0.7 and 1
d. increases with the increase in body size
8.15. Large-size mammalian species, by comparison to small-size species, have lower
a. resting metabolic rate (per unit of body weight)
b. resting pulmonary ventilation (per unit of body weight)
c. breathing frequency
d. tidal volume (per unit of body weight)
8.16. In adult mammals at rest pulmonary ventilation is
a. a mechanism of gas convection
b. proportional to dead space ventilation
c. directly proportional to metabolic rate
d. directly proportional to body size
8.17. With a respiratory quotient (R.Q.) of 0.85
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312B – Practice questions– p.46
a. at each breath, expired volume is slightly less than the inspired volume
b. lung volume decreases progressively breath-by-breath
c. oxygen consumption exceeds carbon dioxide production
d. the expiratory time is shorter than the inspiratory time
8.18. The Q10
a. quantifies the effect of temperature on biological processes
b. averages ≥ 2 in temperature non-regulating organisms
c, when <2 suggests the existence of a temperature control mechanism
d- varies depending on the temperature range considered
8.19. Which of the following statement(s) is/are correct regarding the brown fat (BAT, brown
adipose tissue)
a. produces ATP and heat
b. is particularly abundant in newborns
c. produces heat by extramitochondrial uncoupling of oxidative phosphorylation
d.is autonomically regulated
8.20. As ambient temperature increases above body temperature, the organism’s heat loss can
occur by:
a. Radiation
b. Convection
c. Conduction
d. Evaporation
9.1. (Type A) The physical definition of Pressure (P) is
a. the same as that of force (F)
b. the same as that of tension (T)
c. force multiplied by unit area (F·A)
d. force applied to a unit area (F/A)
e. force times displacement (F·d)
9.2. The response to hypercapnia (1 to 4% inspired CO2) in a normal adult man at comfortable
ambient temperature is characterized by
a. drop in body temperature
b. no change in breathing rate
c. decrease in metabolic rate
d. linear increase in ventilation
9.3. (Type A) In the venous blood the total gaseous pressure is less than in the arterial blood
because of the
a. lymphatic drainage
b. negative pleural pressure
c. difference between the oxygen and carbon dioxide partial pressure-content curves
d. exchange of Cl- and HCO3- between red cells and plasma
e. difference in mean vascular pressure between arterial and venous districts.
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312B – Practice questions– p.47
9.4. A normal adult man is breathing pure oxygen for 2 minutes. You would expect
a. a transient decrease in pulmonary ventilation
b. clinical manifestations of pulmonary oxygen toxicity (e.g., pulmonary edema)
c. a large increase (> 200 mm Hg) in the arterial partial pressure of oxygen
d. an important increase in the arterial content of oxygen (>5 ml %)
9.5. A normal adult man is breathing pure oxygen for about 2 minutes. You would expect
a. a major improvement in the performance of long distance (marathon) running
b. some increase in arterial carbon dioxide pressure (PaCO2)
c. an increase in the number of sighs (deep breaths)
d. some reduction in pulmonary ventilation
9.6. (Type A) A normal adult man has been breathing pure oxygen for about 15 minutes. At this
point, his pulmonary ventilation is increased above the pre-hyperoxic level because
a. CO2 retention at the level of the central chemoreceptors
b. O2-toxicity
c. stimulation of the rapidly adapting receptors
d. increase sensitivity of the carotid body
e. increased censitivity of the central chemoreceptors
9.7. (Type A). A patient is in coma, intubated and artificially ventilated by a mechanical
respirator connected to his endo-tracheal tube. Which of the following suggests that the patient is
ventilated more than he needs to be
a. positive swings in pleural pressure in excess of 10 cm H2O
b. airways pressure reaching high positive values (e.g. >10 cm H2O)
c. absence of patient’s attempts to breathe on his own
d. the arterial pressure of oxygen exceeding 100 mm Hg
e. the arterial pressure of carbon dioxide lower than 30 mm Hg
9.8. (Type A) Acute (about 15 min) exposure to hypoxia (alveolar PO2 = 50 mm Hg) in a normal
subject causes
a. a decrease in pH of the cerebro-spinal fluid
b. a decrease in arterial pH
c. decreased activity of the peripheral chemoreceptors
d. decreased activity of the central (medullary) chemoreceptors
e. an increase in arterial PCO2
9.9. The peripheral chemoreceptors
a. respond to changes in arterial pH and O2
b. have extraordinarily high blood flow per gram of tissue
c. for the same change in arterial PO2 (ΔPaO2), their ‘sensitivity’ increases progressively more
the lower the PaO2
d. are the most important chemosensors for the ventilatory response to hypercapnia
9.10. The ventilatory response to CO2
a. increases its ‘sensitivity’ at high levels of arterial oxygen pressure (PaO2)
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312B – Practice questions– p.48
b. is reduced during sleep
c. is eliminated in absence of the peripheral chemoreceptors
d. is believed to be different (in threshold and or slope) in diving mammals
9.11. A human infant becomes hypoxic but his pulmonary ventilation is not higher than during
normoxia. His body temperature is lower than normal. The most likely reason(s) for the absent
increase in ventilation is/are
a. the decrease in body temperature
b. the absent response of the central chemoreceptors
c. the absent response of the peripheral chemoreceptors
d. the drop in metabolic rate
9.12. If the interpretation of the condition above (9.11.) is correct, the infant is likely to be
a. hyperventilating
b. normoventilating
c. normothermic (in relation to his hypoxic condition)
d. in severe acidosis
9.13. (Type A) An adult man is unconscious and bleeding because of a severe trauma. In the
minutes immediately following the acute hemorrhage (about 500 ml of blood loss) one should
expect
a. a major increase in tidal volume
b. tackypnea (rapid breathing) with shallow pattern
c. some episodes of apnea (cessation of breathing)
d. no changes in pulmonary ventilation
e. a major (>8 mm Hg) drop in arterial CO2 pressure (PaCO2)
9.14. (Type A) In the operative room a patient has been mechanically ventilated for about thirty
minutes with 30% O2. After stopping the ventilator, the patient is not breathing spontaneously.
Out of many interpretations, the most likely explanation for the patient’s apnea is
a. the patient is cold
b. decrease in metabolic rate
c. over-stimulation of the pulmonary stretch receptors
d. respiratory alkalosis
e. severe hypoxemia
9.15. (Type A) A 35-year old man goes to the hospital emergency room. He claims that 10
minutes earlier he lost a lot of blood (“possibly, half a liter!”) because of an accidental cut to the
tongue. Presently, in the emergency room, the bleeding has ceased. His breathing rate is 17/min
(normal is 14 breaths/min) and tidal volume is only slightly increased (~600 ml; normal is 500
ml). His arterial PaO2 and PaCO2 are, respectively, 98 and 38 mm Hg. His hematocrit is 44%,
hemoglobin 15 dl/100 ml. Which of the following statements best describes the situation?
a. the patient needs an immediate blood transfusion
b. the patient cannot have lost that amount of blood, but probably only less than a few ml
c. the patient is hypoventilating and needs immediate respiratory assistance
d. blood gases contradict the patient’s story
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312B – Practice questions– p.49
e. all data are compatible with the story told by the patient
9.16. During hypoxia, the occurrence of hypometabolism should imply
a. less hyperventilation than if hypometabolism did not occur
b. greater hypoxemia (i.e., lower arterial PO2)
c. some accumulation of anaerobic by-products (e.g., lactic acid)
d. lesser increase in pulmonary ventilation
[do not confuse the term ‘hyperpnea’ with the term ‘hyperventilation’]
9.17. A decrease in ventilatory chemosensitivity (VE response to an increase in carbon dioxide, a
decrease in oxygen, or both) is expected to occur in
a. patients with low lung compliance
b. mammals frequently living in burrows
c. aquatic mammals
d. people long-acclimatized to high altitude
9.18. A major decrease in hemoglobin concentration in the blood (e.g., from 16 to 8 g %), other
parameters being constant, should
a. halve the value of hematocrit
b. double breathing frequency
c. increase the respiratory quotient (carbon dioxide production-oxygen consumption ratio)
d. increase metabolic rate
9.19. Which of the following is likely to decrease the arterial oxygen pressure (PaO2)
a. anemia
b. right-to-left shunt
c. carbon monoxide poisoning
d. high altitude
9.20. (Type A) A patient at rest is breathing air at sea level. His alveolar oxygen pressure (PAO2)
is 60 mmHg and arterial oxygen pressure (PaO2) of 56 mmHg. The most likely explanation for
these values is
a. diffusion limitation
b. right-to-left shunt
c. ventilation-to-perfusion non-uniformity
d. hypoventilation
e. severe anemia
[Consider that an alveolar-arterial O2 difference of <5 mmHg is considered within the normal range].
10.1. An adult man reached a high-altitude location (4,330 m). The first day at high altitude his
resting pulmonary ventilation was 8 liters/min. After two weeks his ventilation was 11 liters/min.
The increase in ventilation during the two weeks at high altitude can be explained by
a. gradual re-acidification of the cerebral-spinal fluid
b. gradual re-acidification of the arterial blood
c. gradual increased activity of the carotid bodies
d. progressive adaptation of the respiratory muscles
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312B – Practice questions– p.50
10.2. In a 50-year old high-lander (a man who was born and lived his whole life at high altitude)
you would expect to find (by comparison to a same-age sea-level dweller who arrived two
months earlier to the same altitude)
a. lower pulmonary ventilation
b. normal lung compliance
c. higher arterial pressure of carbon dioxide (PaCO2)
d.higher hemoglobin affinity for oxygen (low P50)
10.3. A 35 year old woman, apparently healthy, has been living in a resort area at high altitude
(3,200 m) for almost 1 year. You would expect to find
a. pulmonary ventilation higher than during her first day at high altitude
b. oxygen consumption similar to her sea-level value
c. arterial pressure of carbon dioxide (PaCO2) lower than during her first day at high altitude
d. hematocrit higher than during the first day at high altitude
(10.4) At high altitude
a. the partial pressure of water vapor (at any given body temperature) is lower than at sea-level
b. the carotid bodies are likely to be more active than at sea level
c. pulmonary edema (fluid in the lung interstitium or in the alveoli) is less likely to occur than at
sea-level
d. most subjects have some degree of respiratory alkalosis
[consider the changes in pulmonary circulation at high altitude]
10.5. At very high altitudes (5000-8000 m) ambient temperature usually is lower than at sea
level. The most likely reason(s) for this is/are
a. lower heat radiation from earth to atmosphere
b. the presence of ice and snowfields
c. the drop in temperature with the decrease in atmospheric pressure
d. the effect of oxygen level on temperature
10.6. A subject increases breathing rate, but not tidal volume, with respect to his breathing
pattern during resting conditions. Metabolic rate remained unchanged and the arterial partial
pressure of CO2 decreased. The following term(s) would be correct to describe his new breathing
condition
a. hyperventilation
b. tachypnea
c. hyperpnea
d. respiratory alkalosis
[recall the meaning of the term ‘hyperventilation’]
10.7. Hyperventilation is expected to occur during
a. cold-induced thermogenesis
b. chronic hypoxia
c. moderate muscle exercise
d. chronic hypercapnia
10.8. During sustained (2 hours) hypoxia in mammals the following can occur
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312B – Practice questions– p.51
a. hyperventilation (i.e., increased alveolar ventilation relative to metabolic needs)
b. hyperpnea (i.e., increase in the absolute value of pulmonary ventilation)
c. hypometabolism
d. increased oxygen extraction (i.e., increased arterial-venous oxygen difference)
10.9. A six month-old infant was born with a cyanotic heart disease because of a right-to-left
inter ventricular shunt. His arterial blood never reached oxygen saturation higher than 70%.
Among his clinical manifestations, you would expect to find
a. increased hemoglobin
b. decreased body growth
c. increased hematocrit
d. respiratory alkalosis
10.10. The ventilatory response to hypoxia
a. is the major ‘drive to breathe’ at high altitude
b. increases in conditions of hypercapnia
c. does not play any role in mild carbon monoxide poisoning
d. is less pronounced in infants than in adults
10.11. At the top of a 3000 meter high mountain, which of the following alveolar partial
pressures would be expected to be lower than normal?
a. oxygen (PA-O2)
b. carbon dioxide (PA-CO2)
c. nitrogen
d. water vapor (PA-H2O)
[Consider that the partial pressure of water vapor depends only on the temperature]
10.12. (Type A) Cyanosis (a bluish color of the skin and mucous membranes) indicates a higher
than normal blood concentration of
a. carbon dioxide
b. carbon monoxide
c. hydrogen ion
d. diphosphoglycerate (DPG)
e. reduced hemoglobin
10.13. Hyperventilation is likely to occur with
a. last third of gestation
b. caffeine injection
c. high fever
d. moderate exercise
10.14. (Type A) The difference between the terms ‘hyperpnea’ and ‘hyperventilation’ depends
on
a. the magnitude of the increase in pulmonary ventilation
b. the magnitude of the increase in breathing frequency
c. whether or not tidal volume is increased
d. whether or not the alveolar pressure of carbon dioxide (PACO2) is decreased
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312B – Practice questions– p.52
c. whether or not the subjects feels the dyspnea
11.1. During exercise-induced hyperpnea, at mild and moderate work loads
a. arterial O2 content increases
b. arterial PCO2 remains constant
c. the arterial-venous difference in O2 content is as at rest
d. mixed venous O2 content decreases
11.2. Maximal oxygen consumption
a. when normalized by body weight, increases in the older age
b. in normal 20-30 year-old humans averages about 4-5 ml/kg/min
c. after body weight normalization, usually is higher in young women than in young men of the
same age
d. usually is the same as maximal carbon dioxide production
11.3. During walking, the energy cost of transportation (Cal/kg/km)
a. on a flat surface, at very low walking speeds (e.g., at speeds < 1 km/hr) is higher than at the
optimal walking speed (5 km/hr)
b. increases at very high walking speeds (e.g., at speeds > 8 km/hr)
c. at high speeds (e.g., at speeds >12 km/hr) can exceed the cost of running
d. during downhill walks on very steep slopes (e.g., slopes > 40%) becomes very small or
negligible
11.4. The ventilation-oxygen consumption (VE - VO2, Y and X axis, respectively) relationship
a. at high level of work-loads becomes concave toward the VE-axis
b. is linear for mild and moderate levels of exercise
c. is more steep in sedentary persons than in athletes
d. at the highest workloads, is influenced by the production of lactic acid
11.5. Muscle exercise is one of the most powerful stimuli on pulmonary ventilation. Primarily,
such stimulus originates from the
a. drop in arterial partial pressure of oxygen (PaO2)
b. increased arterial partial pressure of carbon dioxide (PaCO2)
c. afferents (proprioceptors) of the chest wall
d. afferents (pulmonary stretch receptors) from the lungs
11.6. (Type A) At the end of muscle exercise of moderate intensity pulmonary ventilation
remains elevated for some time
a. as part of the phenomenon of “payment back the oxygen debt”
b. because of the lactic acid accumulated during the exercise
c. because of the post-exercise persisting excitation of the neuro-muscular pathways
d. because cardiac output remains elevated for some time
e. Not true. Pulmonary ventilation falls to the control (resting) level instantaneously.
11.7. (Type A) The terminology “payment back of the oxygen debt” refers to the
a. increased aerobic metabolism necessary to replenish anaerobic energy sources
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312B – Practice questions– p.53
b. increased pulmonary ventilation (VE) to compensate for the drop in arterial oxygen content
c. rapid increase in ventilation at the onset of muscle exercise
d. activation of anaerobic energy supply during hypoxia
e. onset of muscle exercise, when pulmonary ventilation lags behind the rise in metabolism
11.8. During maximal levels of exercise in normal adult men the value of ventilation
a. requires the activation of the expiratory muscles
b. is not limited by pulmonary airflow resistance
c. is not limited by the compliance of the respiratory system
d. can require an important fraction (>more than 10%) of the total oxygen consumption
11.9. In a muscle during maximal exercise one expects a drop in the affinity of hemoglobin for
O2 because of
a. increased temperature
b. decrease in oxygenation
c. lactic acid production
d. vascular shunts
11.10. An adult man is running at a steady pace. His metabolic rate is twice its resting value. You
would expect
a. alveolar ventilation to be twice the resting value
b. arterial partial pressure of oxygen to be as at rest
c. arterial partial pressure of carbon dioxide to be as at rest
d. some degree of metabolic acidosis
11.11. An adult man is running a 3000 m competition. His metabolic rate is twelve times its
resting value. You would expect
a. alveolar ventilation to be >12 times the resting value
b. arterial partial pressure of oxygen to be as at rest
c. arterial partial pressure of carbon dioxide to be lower than at rest
d. some degree of metabolic acidosis
11.12. During moderate aerobic exercise an athlete, by comparison to a sedentary individual
performing the same exercise, is expected to have
a. higher oxygen consumption
b. lower anaerobic threshold
c. lower arterial PCO2
d. lower ventilation
11.13. Maximal oxygen consumption (VO2max, ml/min)
a. rises in adolescence, then declines with old age
b. as exercise progresses, is reached just before the onset of acidemia (lactic acid production)
c. is higher in males than in females of similar age
d. can be predicted from the maximal ventilation of the subject
11.14. (Type A) A subject, while exercising on a cycle-ergometer, is experiencing dyspnea (an
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312B – Practice questions– p.54
unpleasant sensation of shortness of breath). This sensation is relieved when he breathes a
mixture of 70% Helium-30% Oxygen. The most likely reason for the relief while breathing the
He:O2 mixture is
a. the low temperature of the gas mixture
b. an improvement in lung compliance
c. the increase in arterial oxygen pressure
d. the total absence of CO2 in the gas mixture
e. the decrease in airways resistance
11.15. (Type A) A subject is running in cold weather. His metabolic rate doubles; also
ventilation is expected to increase. A perfect coupling between metabolic rate and ventilation
would best be described by
a. arterial PCO2 (PaCO2) at the normal (resting) value
b. constancy of arterial PO2 (PaO2)
c. no changes in body temperature
d. doubling of minute ventilation
e. a constant respiratory exchange ratio
11.16. (Type A) A well-conditioned 18 yr old student jogs around the block at about5 km/hr. At
rest, she had normal values of carbon dioxide production (VCO2, 200 ml/min) and of alveolar
ventilation (VA, 4.3 L/min). What would be her most likely set of values just before she finishes
running?
a. PaCO2 (arterial pressure of CO2) 25 mmHg; VA 8.6 L/min; VCO2 400 ml/min
b. PaCO2 40 mmHg; VA 8.6 L/min; VCO2 400 ml/min
c. PaCO2 40 mmHg; VA 4.3 L/min; VCO2 400 ml/min
d. PaCO2 40 mmHg; VA 8.6 L/min; VCO2 200 ml/min
e. PaCO2 50 mmHg; VA 8.6 L/min; VCO2 400 ml/min
11.17. (Type A). An adult (60 kg) man is walking on a flat surface at the optimal speed (4
km/hr), while eating a medium-size (200 g) pizza. The calories of his meal should provide
enough energy for a walking distance of about
a. about 250 m
b. about half km
c. no more than 1 km
d. about 5 km
e. at least 10 km
11.18. During exercise
a. oxygen consumption can increase more than tenfold compared to rest
b. the respiratory exchange ratio invariably is lower than 1
c. ventilation can increase more than cardiac output does
d. the rise in ventilation can be fully explained by the fall in arterial pH
11.19. (Type A) Exercise is a very powerful stimulus on ventilation. It primarily works by way
of
a. inputs from the cerebellum
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312B – Practice questions– p.55
b. the rise in blood lactic acid
c. the rise in blood K+
d. inputs from the limbic cortex
e. none of the above
11.20. Which of the following will increase minute ventilation?
a. Cold exposure.
b. Progesterone.
d. Exercise.
e. Chronic hypoxia.
12.1 (Type A). The umbilical artery of the mammalian fetus carries blood
a. reach in O2 and poor in CO2 (arterialized blood)
b. reach in CO2 and poor in O2 (venous blood)
c. poor in O2 and alkalotic
d. reach in O2 and acidotic
e. with O2 and CO2 content virtually identical to the umbilical vein
12.2. (Type A). The gas exchange in the earliest phases (first days) of mammalian
embryogenesis
a. occurs by gas diffusion
b. is helped by pulmonary gas convection
c. occurs by active transport of the gases through the placenta
d. is severely limited by the lack of hemoglobin
e. is not necessary
12.3. The lungs of a mammalian fetus during the second third of gestation
a. are liquid-filled
b. do not have surfactant
c. have just a few of the most peripheral airways
d. produce large quantities of antioxidants
12.4. In the newborn mammal, the formation of functional residual capacity (FRC)
a. begins with the first postnatal breaths
b. is facilitated by the presence of surfactant
c. is facilitated by the elimination of the pulmonary fluid
d. is more rapid in those neonates born with very high chest wall compliance
12.5. In mammals, the first inspiration at birth
a. requires a large (> 5 cm H2O) drop in pleural pressure
b. encounters high airflow resistance
c. contributes to the formation of surface tension in the peripheral airways
d. has a change in air volume larger than in the following expiration
12.6. In newborns
a. the hemoglobin has low O2 affinity (high P50)
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312B – Practice questions– p.56
b. the ‘sensitivity’ of chemoreceptors is lower than in adults
c. the stimulus threshold of the pulmonary mechanoreceptors is lower than in adults
d. pulmonary anti-oxidants are expressed more than in adults
12.7. The high resistance of newborns to oxygen toxicity can be attributed to
a. their small size
b. their low metabolic rate
c. the incomplete formation of alveoli and peripheral airways
d. the high expression of pulmonary anti-oxidants
12.8. (Type A). The best explanation for the newborn’s propensity to distort the chest wall
during breathing is
a. high chest wall compliance
b. high lung compliance
c. large pleural pressure swings
d. high peripheral airway resistance
e. high chest wall-lung compliance ratio
12.9. In infants during breathing, functional residual capacity (FRC) is maintained higher than
the resting passive volume of the respiratory system because of the following mechanism(s)
a. high breathing frequency
b. post-expiratory activity of the expiratory muscles
c. glottis (laryngeal) control of the expiratory flow
d. high chest wall compliance
12.10. Hypoxic hypometabolism
a. usually is accompanied by a decrease in body temperature
b. contributes to the hypoxic hyperventilation
c. in young organisms is accompanied by a decrease in body growth
d. is accompanied by severe lactic acidosis
12.11. Typically, newborn mammals are characterized by
a. hypometabolic response to hypoxia
b. high chest wall-lung compliance ratio
c. incomplete formation of alveoli and peripheral airways
d. high hemoglobin affinity for oxygen
12.12. (Type A) The low value of the arterial partial pressure of oxygen (PaO2) in newborns is
mostly caused by
a. low hemoglobin
b. low number of alveoli
c. circulatory venous-arterial shunts
d. low pulmonary ventilation
e. low heart rate
12.13. Administration of pure oxygen to a hypoxic newborn infant caused only a minimal
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312B – Practice questions– p.57
increase in the arterial partial pressure of oxygen (PaO2). This can be attributed to
a. pulmonary fluid in the airways
b. low functional residual capacity (FRC)
c. pulmonary diffusion limitation
d. venous-arterial shunts
12.14. The formation of an adequate functional residual capacity (FRC) at birth
a. favors the buoyancy of aquatic mammals
b. lowers the work of breathing
c. provides a reserve of oxygen during apnea
d. diminishes the oscillations of blood gases during breathing
12.15. The most likely mechanism(s) for the onset of continuous pulmonary ventilation at birth is
(are)
a. the increase in oxygenation
b. changes in thermal stimuli
c. the new tactile and pressure stimuli
d. the rise in metabolic rate
12.16. Fetal breathing movements
a. can be detected since the earliest phase of fetal development
b. help the control of pulmonary fluid
c. change from intermittent to continuous during the middle of gestation
d. are important for lung growth
12.17 (Type A) With respect to fetal circulation, what would be the location with the highest O2
saturation?
a. Umbilical artery
b. Left atrium
c. Descending aorta
d. Inferior vena cava
e. Ductus arteriosus
[Consider that in the fetus gas exchange occurs in the placenta, and the right-left shunts typical of fetal
circulation]
12.18. Which of the following represents a "right-to-left shunt"?
a. pulmonary blood flow through a region of lung atelectasis (alveolar collapse)
b. blood flow from the systemic to pulmonary circulation through a hole in the interventricular
septum
c. blood flow from the pulmonary artery to the aorta through the ductus arteriosus
d. blood flow from skin arteries to skin veins, bypassing the skin capillaries
12.19. (Type A) Suppose a person has a genetic defect causing him to continue to produce fetal
hemoglobin (rather than the normal hemoglobin) throughout adult life. What would be the
expected systemic arterial oxygen partial pressure (PaO2) and saturation (HbO2) compared to a
normal person)?
a. higher PaO2 and higher Hb O2 saturation
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312B – Practice questions– p.58
b. higher PaO2 but lower Hb O2 saturation
c. lower PaO2 but higher Hb O2 saturation
d. lower PaO2 and lower Hb O2 saturation
e. normal PaO2 but higher Hb O2 saturation
[Consider that the partial pressure of a gas in a liquid is determined solely by its physically dissolved
component, not by its total content]