Chapter 17
The Respiratory System
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Lesson 17.1
Anatomy of the Respiratory System and Upper
Respiratory Disorders
1.
Discuss the generalized functions of the respiratory
system, list the major organs of the respiratory system
and describe the function of each, and describe the
major disorders of the upper respiratory tract.
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2
Structural Plan
 Basic plan of respiratory system would be similar
to an inverted tree if it were hollow; leaves of the
tree would be comparable to alveoli, with the
microscopic sacs enclosed by networks of
capillaries
 Diffusion is the mode for gas exchange that
occurs in the respiratory mechanism
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3
Structural Plan of the Respiratory
Organs
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4
The Gas-Exchange Structures of
the Lung
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5
Respiratory Tracts
 Upper respiratory tract—nose,
pharynx, and larynx
 Lower respiratory tract—trachea,
bronchial tree, and lungs
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Respiratory Mucosa
 Mucous membrane that lines the air distribution
tubes in the respiratory tree
 More than 125 ml of mucus produced each day forms
a “mucus blanket” over much of the respiratory
mucosa
 Mucus serves as an air purification mechanism by
trapping inspired irritants such as dust and pollen
 Cilia on mucosal cells beat in only one direction,
moving mucus upward to pharynx for removal
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Respiratory Mucosa Lining the Trachea
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Nose
 Structure
 Nasal septum separates interior of nose
into two cavities
 Mucous membrane lines nose
 Frontal, maxillary, sphenoidal, and
ethmoidal sinuses drain into nose
 Nasal polyps—noncancerous growths that
project from nasal mucosa (associated with
chronic hay fever)
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The Paranasal Sinuses
•
The paranasal sinuses and the lacrimal sacs drain into the
nasal cavity
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Functions of the Nose
 Warms and moistens inhaled air
 Contains sense organs of smell
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Structure of the Pharynx
Pharynx (throat) about 12.5 cm (5
inches) long
 Divided into nasopharynx,
oropharynx, and laryngopharynx
 Two nasal cavities, mouth, esophagus,
larynx, and auditory tubes all have
openings into pharynx

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Structure of the Pharynx, Cont'd.
 Pharyngeal tonsils and openings of
auditory tubes open into
nasopharynx; other tonsils found in
oropharynx
 Mucous membrane lines pharynx
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13
Sagittal Section of the Head and Neck
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Functions of the Pharynx
 Passageway for food and liquids
 Air distribution; passageway for air
 Tonsils—masses of lymphoid tissue
embedded in pharynx provide immune
protection
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Tonsillitis
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Structure of the Larynx
 Located just below pharynx; also referred to as
the voice box
 Several pieces of cartilage form framework
 Thyroid cartilage (Adam’s apple) is largest
 Epiglottis partially covers opening into larynx
 Mucous lining
 Vocal cords stretch across interior of larynx; space
between cords is the glottis
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17
The Larynx
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Functions of the Larynx
 Air distribution; passageway for air
to move to and from lungs
 Voice production
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Laryngeal Cancer
 Incidence increases with age and
alcohol abuse
 Occurs most often in men over age 50
 If larynx removed, “esophageal speech”
or electric artificial larynx needed for
speech
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20
Upper Respiratory Infections (URIs)
• Rhinitis—nasal inflammation, as in a
•
cold, influenza, or allergy
• Infectious rhinitis—common cold
• Allergic rhinitis—hay fever
Pharyngitis (sore throat)—inflammation
or infection of the pharynx
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Laryngitis
 Inflammation of the larynx resulting
from infection or irritation
 Epiglottitis—life-threatening condition
caused by Haemophilus influenzae type B
(Hib) infection
 Croup—not life-threatening type of
laryngitis caused by parainfluenza viruses
producing a barking cough
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Anatomical Disorders
 Deviated septum—septum that is abnormally far from the
midsagittal plane (congenital or acquired)
 Epistaxis (bloody nose) can result from mechanical injuries
to the nose, hypertension, or other factors
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Trachea
 Structure
 Tube (windpipe) about 11 cm (4.5 inches) long
that extends from larynx into the thoracic cavity
 Mucous lining
 C-shaped rings of cartilage hold trachea open
 Function—passageway for air to move to and
from lungs
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Cross Section of the Trachea
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Obstruction of the Trachea
 Blockage of trachea occludes the airway, and if
complete, causes death in minutes
 Tracheal obstruction causes more than 4000
deaths annually in the United States
 The Heimlich maneuver is a lifesaving technique
used to free the trachea of obstructions; also
called abdominal thrusts
 Tracheostomy—surgical procedure in which a
tube is inserted into an incision in the trachea so
that a person with a blocked airway can breathe
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A tracheostomy tube in place
What structure
is posterior to
the trachea?
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Structure of the Bronchi, Bronchioles,
and Alveoli
 Trachea branches into right and left bronchi
 Right primary bronchus more vertical than left
 Aspirated objects most often lodge in right
primary bronchus or right lung
 Each bronchus branches into smaller and smaller
tubes (secondary bronchi), eventually leading
to bronchioles
 Bronchioles end in clusters of microscopic
alveolar sacs, the walls of which are made up of
alveoli
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Alveoli
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Functions of Bronchi, Bronchioles, and
Alveoli
 Bronchi and bronchioles—air distribution;
passageway for air to move to and from alveoli
 Alveoli—exchange of gases between air and
blood
 Type II cells in the alveoli produce surfactant to
help reduce surface tension or "stickiness"
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Respiratory Distress
 Relative inability to inflate the alveoli
 Infant respiratory distress syndrome (IRDS)—
leading cause of death in premature infants
resulting from lack of surfactant production in
alveoli
 Adult respiratory distress syndrome (ARDS)—
impairment of surfactant by inhalation of foreign
substances or other conditions
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Structure of the Lungs
 Size—large enough to fill the chest cavity, except
for middle space occupied by heart and large
blood vessels
 Apex—narrow upper part of each lung, under
collarbone
 Base—broad lower part of each lung; rests on
diaphragm
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Lungs
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Structure of the Pleura
 Moist, smooth, slippery membrane that lines chest
cavity and covers outer surface of lungs; reduces
friction between the lungs and chest wall during
breathing
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Lungs and Pleura
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Lungs and Pleura
 Function—breathing (pulmonary ventilation)
 Pleurisy—inflammation of the pleura
 Atelectasis—incomplete expansion or
collapse of the lung (alveoli); can be caused
by:
 Pneumothorax—presence of air in the
pleural space
 Hemothorax—presence of blood in the
pleural space
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Pneumothorax
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Lesson 17.2
Respiration, Gas Exchange & Lower Respiratory Tract Disorders
Compare, contrast, and explain the mechanism
responsible for the exchange of gases that occurs
during internal and external respiration.
3. Describe the transport of gasses by blood, and list and
discuss the volumes of air exchanged during
pulmonary ventilation.
4. Identify and discuss the mechanisms that regulate
respiration, and identify breathing patterns.
5. Identify and describe the major disorders of the lower
respiratory tract.
2.
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Respiration
 Mechanics of breathing
 Pulmonary ventilation includes two phases called
inspiration (movement of air into lungs) and
expiration (movement of air out of lungs)
 Changes in size and shape of thorax cause changes in
air pressure within that cavity and in the lungs
because as volume changes, pressure changes in the
opposite direction
 Air moves into or out of lungs because of pressure
differences (pressure gradient); air moves from high
air pressure toward low air pressure
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Mechanics of Breathing
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Inspiration
 Active process— muscles increase volume of thorax,
decreasing lung pressure, which causes air to move from
atmosphere into lungs (down the pressure gradient)
 Inspiratory muscles include diaphragm and external
intercostals
 Diaphragm flattens during inspiration—increases top-to-
bottom length of thorax
 External intercostals—contraction elevates the ribs and
increases the size of the thorax from front to back and from
side to side
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Expiration
 Reduction in the size of the thoracic cavity
decreases its volume and thus increases its
pressure, so air moves down the pressure gradient
and leaves the lungs
 Quiet expiration ordinarily a passive process
 During expiration, thorax returns to its resting size
and shape
 Elastic recoil of lung tissues aids in expiration
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Expiration
 Expiratory muscles used in forceful expiration are
internal intercostals and abdominal muscles
 Internal intercostals—contraction depresses the
rib cage and decreases the size of the thorax from
front to back
 Abdominal muscles—contraction elevates the
diaphragm, thus decreasing size of the thoracic
cavity from top to bottom
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Exchange of Gases in Lungs
 Oxygen moves from alveoli into lung capillaries
 Hemoglobin combines with oxygen, producing
oxyhemoglobin
 Carbaminohemoglobin breaks down into
carbon dioxide and hemoglobin
 Carbon dioxide moves out of lung capillary blood
into alveolar air and out of body in expired air
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Exchange of Gases in Lungs & Tissue
Capillaries
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Exchange of Gases in Tissues
 Oxyhemoglobin breaks down into oxygen and
hemoglobin
 Oxygen moves out of tissue capillary blood into
tissue cells
 Carbon dioxide moves from tissue cells into tissue
capillary blood
 Hemoglobin combines with carbon dioxide,
forming carbaminohemoglobin
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Blood Transportation of Gases
 Transport of oxygen
 Only small amounts of oxygen (O2) can be dissolved
in blood
 Most oxygen combines with hemoglobin to form
oxyhemoglobin (HbO2) to be carried in blood
 Transport of carbon dioxide
 Dissolved carbon dioxide (CO2) in plasma—10%
 Carbaminohemoglobin (HbCO2)—20%
 Dissolved in blood fluids and converted to
Bicarbonate ions (HCO3−)—70%
H2O + CO2 <-> H2CO3 <-> H + HCO3Water
carbon dioxide
carbonic acid
hydrogen bicarbonate
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The Process of Respiration
Gas Exchange
 Requires a pressure gradient
 External respiration (exchange)—between lung
alveoli and capillary blood
 Oxygen leaves alveoli and enters capillaries.
 Carbon dioxide leaves capillaries and enters alveoli.
 Internal respiration (exchange)—between blood and
tissues
 Oxygen leaves capillaries and enters tissue.
 Carbon dioxide leaves tissue and enters capillaries.
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Volumes of Air Exchanged in
Pulmonary Ventilation
Volumes of air exchanged in breathing can be
measured with a spirometer
 Tidal volume (TV)—amount normally
breathed in or out with each breath
 Vital capacity (VC)—largest amount of air
that one can breathe out in one expiration
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Volumes of Air Exchanged in
Pulmonary Ventilation, Cont'd.
 Expiratory reserve volume (ERV)—amount of air
that can be forcibly exhaled after expiring the tidal
volume
 Inspiratory reserve volume (IRV)—amount of air
that can be forcibly inhaled after a normal
inspiration
 Residual volume (RV)—air that remains in the
lungs after the most forceful expiration
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Pulmonary Ventilation Volumes
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Regulation of Respiration



Regulation of respiration permits the body to adjust to
varying demands for oxygen supply and carbon dioxide
removal
Brainstem—central regulatory centers are called
respiratory control centers (inspiratory and expiratory
centers)
Medullary centers—under resting conditions the
medullary rhythmicity area produces a normal rate and
depth of respirations (12 to 18 per minute) The two most
important control centers for regulating breathing rhythm
in the medulla are
•
•
ventral respiratory group (VRG) for basic breathing patterns
dorsal respiratory group (DRG) adjusting breathing with an
increase in RR with increase in PH
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Central Regulatory Centers


Pontine centers—as conditions in the body
vary, these centers in the pons can alter the
activity of the medullary rhythmicity area, thus
adjusting breathing rhythm
Brainstem centers are influenced by
information from other parts of the brain and
from sensory receptors located in other body
areas
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Regulation of Respiration
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Regulation of Respiration, Cont'd.


Cerebral cortex—voluntary (but limited)
control of respiratory activity
Receptors influencing respiration
•
•
Chemoreceptors—respond to changes in carbon
dioxide, oxygen, and blood acid levels; located in
carotid and aortic bodies
Pulmonary stretch receptors—respond to the
stretch in lungs, thus protecting respiratory organs
from over inflation
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Regulation of Respiration (cont.)
Breathing Patterns
Measured in breaths per minute
 Adults: 12 to 20
 Children: 20 to 40
 Infants: more than 40
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Breathing Patterns






Eupnea—normal breathing
Hyperventilation (Tachypnea)
—rapid and deep respirations
Hypoventilation—slow and shallow
respirations
Dyspnea—labored or difficult respirations
Orthopnea—dyspnea relieved by moving into
an upright or sitting position
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Breathing Patterns, Cont'd.




Apnea—stopped respiration
Cheyne-Stokes respiration (CSR)—cycles of
alternating apnea and hyperventilation
associated with critical conditions
Kussmaul respiration— deep rapid
respirations seen with acidosis (DKA)
Respiratory arrest—failure to resume
breathing after a period of apnea
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Regulation of Respiration (cont.)
Abnormal Ventilation
 Hyperventilation
 High oxygen level and low CO2 level (hypocapnia)
 Increases blood pH (alkalosis)
 Hypoventilation
 Insufficient air in alveoli
 Decreases blood pH (acidosis)
 Results of hypoventilation:



Cyanosis
Hypoxia
Hypoxemia
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Respiratory Disorders (cont.)
Infection
 Common cold
 Respiratory syncytial virus (RSV)
 Croup
 Influenza
 Pneumonia
 Lobar pneumonia
 Bronchopneumonia
 Pneumocystis pneumonia
 Tuberculosis
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Pneumonia
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Respiratory Disorders (cont.)
Sudden Infant Death Syndrome (SIDS)
 Also called crib death
 Unexplained death
 Seemingly healthy infant
 Under 1-year-old
 Usually occurs in sleep
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Respiratory Disorders (cont.)
Allergic Rhinitis (Hay Fever)
 Hypersensitivity to allergens
 Watery discharge from eyes and nose
 Seasonal or chronic
Asthma
 Inflammation of airway tissues
 Spasm in bronchial tubes
 May be related to hypersensitivity to allergens
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Respiratory Disorders (cont.)
Chronic Obstructive Pulmonary Disease (COPD)
 Includes both chronic bronchitis and emphysema
 Normal air flow obstructed
 Reduced exchange of oxygen and carbon dioxide
 Air trapping and overinflation of lungs
 Dyspnea
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Respiratory Disorders (cont.)
Cancer
 Lung cancer
 Most common cause of cancer-related deaths.
 Most important cause is cigarette smoking.
 Cancer of larynx
 Linked to cigarette smoking and alcohol consumption
 High cure rate
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Bronchogenic carcinoma.
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