Respiratory System
1
Respiratory System
1.
A function of the structure labelled X is to
A. produce sound.
B. exchange gases.
C. carry air into and out of the lung.
D. stimulate the breathing centre in the brain.
2.
3.
4.
Identify structure X in the above diagram and relate its structure to its
function (3 marks)
• Alveoli
• Large surface area for efficient diffusion of O2 and CO2
• Highly vascularized therefore a large supply of blood can
bring CO2 and take O2 to the tissues of the cells
• Produces lipoprotein which reduces surface tension thus
preventing alveolar walls from sticking together
• Contain stretch receptors that send a signal back to medulla
oblongata which stops the inhalation signal that is sent out by
the medulla oblangata
Describe how the upper respiratory tract is specialized to keep the lungs free of debris (3 marks)
• Mucus in nasal cavities traps dust and debris
• Trachea also contains mucus for trapping dust and debris
• Trachea has cilia which sweeps up debris away from the lungs
Which of the following would cause the
effect shown?
A. increased oxygen in the blood
B. increased numbers of red blood cells
C. increased carbon dioxide in the
blood
D. decreased concentration of hydrogen
ions
5.
Which of the following reactions occurs in a capillary of the leg?
A. Hb + H+ Æ HHb
B. HbCO2 Æ Hb + CO2
C. Hb + oxygen Æ HbO2
D. H+ + HCO3– Æ H2CO3
Respiratory System
6.
7.
2
Identify three substances transported by hemoglobin in the blood and give the name of each
form of hemoglobin. (3 marks: ½ mark each)
• Oxyhemoglobin (HbO2) –transports oxygen
• Reduced hemoglobin (HHb) – transports H+
• Carbaminohemoglobin (HbCO2) – transports CO2
a) Explain how each of the following structures functions in the process of inhalation.
(3 marks)
• Diaphragm: contracts and moves down resulting in negative pressure in the thoracic cavity
which causes air to move into the lungs
• Ribs: attached to the intercostals muscles which cause the chest to expand
• Pleural membranes: enclose the lungs in an air tight seal
8.
a) Label structures W, X, Y and Z on the
diagram. (4 marks: 1 mark each)
W:alveoli
X: medulla oblongata
Y: intercostals muscles (accept ribs)
Z: diaphragm
b) Describe the roles of structures W, X and
Z in the process of inhalation. (3 marks)
• The medulla oblongata sends a
nerve impulse to the diaphragm and
the intercostals muscles in the rib
cage.
• The diaphragm moves down and
the intercostals muscles cause the
ribcage to move out and up.
• This results in expansion of the
thoracic cavity and negative
pressure in the lungs thus air is
draw in.
9.
The structure that increases thoracic volume when it contracts is
A. W
B. X
C. Y
D. Z
Alveoli would not be characterized as
A. muscular.
B. thin-walled.
C. vascularized.
D. secreting a lipoprotein.
Respiratory System
10.
3
Give one function of each of the following. (2 marks: 1 mark each)
a) Cilia in the trachea:
•
move out dust and debris out of the lungs
b)
•
•
•
Hemoglobin:
transport oxygen OR
Transport carbon dioxide OR
Buffer the pH of blood by binding to excess H+ in the blood
11.
The following reaction takes place in the blood:
12.
Substance X would be
A. thrombin.
B. calcium ions.
C. carbonic anhydrase.
The structure labelled X is held open by
A. cartilage.
B. vocal cords.
C. a lipoprotein layer.
D. a pleural membrane.
D. prothrombin activator.
Which of the following is the site of external respiration?
A. Alveoli.
B. Bronchioles.
C. Mitochondria.
D. Muscle tissue.
13.
14.
15.
The graph shows changes in air pressure in the thoracic
cavity during breathing. Which of the
following occurs between times X and Y?
A. Rib muscles relax and diaphragm relaxes.
B. Rib muscles relax and diaphragm contracts.
C. Rib muscles contract and diaphragm relaxes.
D. Rib muscles contract and diaphragm contracts.
An experiment was carried out to determine factors affecting
human blood’s ability to carry
oxygen. The results are shown in the graph above. Which of
the following may have caused
the change at time X?
A. Water was removed from the plasma.
B. More platelets were added to the blood.
C. Stimulation of the medulla oblongata increased breathing
rate.
D. A competitive inhibitor of hemoglobin was added to
the blood.
High concentrations of bicarbonate ion (HCO3-) in the blood will result in
A. increased rate of breathing
B. decreased rate of breathing.
C. increased pressure in the chest cavity.
D. decreased nervous stimulation of the diaphragm.
Respiratory System
16.
Which of the following represents the composition of
blood at X shown in the diagram on the right?
17.
What is the relationship between the following terms as they related to respiratory function?
a) medulla oblongata and diaphragm (2 marks)
•
•
4
medulla oblongata sends a signal to the diaphragm
diaphragm moves down causing negative pressure in the lungs which draws in air
b) intercostal muscles and inspiration (2 marks)
•
•
intercostals muscles move the rib cage out and up
thus expanding the thoracic cavity which causes negative pressure which causes air to
move into the lungs
c) cigarette smoke and trachea (2 marks)
•
•
18.
cigarette smoke destroys functional cilia
therefore mucus containing debris and dust can build up in the respiratory tract
What effect will the wall of the chest cavity being punctured have on the normal body functions in
humans? (2 marks)
•
•
19.
If the chest is punctured then the pleural membranes will also be punctured and there
will not be an air tight seal
Therefore even though the diaphragm and intercostals muscles are working air will not
be drawn in
Describe the role of each of the chemoreceptors in carotid arteries in the normal functioning of the
respiratory system: (1 mark)
•
Chemoreceptors in the carotid arteries detect change in concentration of CO2 and H+ in the
blood and then send a signal to the breathing center in the medulla oblangata
Respiratory System
20.
5
Use your knowledge of respiration to answer the following questions.
a) What are the three most common forms that carbon dioxide is carried in the blood? (3 marks)
•
•
•
HBCO2 (reduced hemoglobin)
H2CO3 (carbonic acid)
HCO3- (bicarbonate ion)
b) Describe the reaction whereby H2O and CO2 are produced in the lung capillaries. ( 1 mark)
The following reaction is driven to the right as CO2 is removed at the lungs
HCO3- + H+ Æ H2CO3 Æ H2O + CO2
c) What is the function of carbonic anhydrase in the above reaction? (1 mark)
•
21.
Carbonic anhydrase speeds up the reaction H2CO3 ↔ H2O + CO2 thus increasing the rate at
which CO2 can be removed from the blood
Describe the role of carbonic anhydrase, carbon dioxide, hydrogen ions and hemoglobin in the
exchange of gases at the tissue level (internal respiration). (5 marks)
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•
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22.
Carbonic anhydrase speeds up the reaction that converts water and carbon dioxide to
carbonic acid : H2O + CO2 Æ H2CO3
Carbonic acid then dissociates as follows: H2CO3 ÆHCO3- + H+
H+ combines with hemoglobin to form HHb (reduced hemoglobin)
The formation of HHb acts as a buffer in the blood thus reducing the affect of H+ on the pH
of blood
Some CO2 will combine with hemoglobin to form carbaminohemoglobin (HbCO2)
A person was brought to the emergency room unconscious. Breathing was shallow and irregular. A
blood sample showed the blood pH to be 7.8 (normal pH = 7.4). A mechanical respirator, which
increases breathing rate, was inserted and sodium bicarbonate was administered intravenously.
a) Explain why the lowered breathing rate lowers the blood pH. (3 marks)
•
•
•
The following reaction occurs at the lungs and is pushed to the right as CO2 is removed
o HCO3- + H+ ↔ H2CO3 ↔ H2O + CO2
Since breathing is shallow and inefficient, CO2 cannot be removed as quickly as it is
produced
Therefore H+ increases and pH is lowered
b) How does the respirator help return the blood pH to normal? (1 mark)
•
The respirator removes CO2 and thus causing the following reaction to be pushed towards
the right HCO3- + H+ Æ H2CO3 Æ H2O + CO2 therefore H+ is removed from the blood
c) What was the reason for administering the sodium bicarbonate? (1 mark)
•
The bicarbonate ion (HCO3-) combines with H+ which removes some of the H+ from the blood