Respiratory Physiology MCQ Questions and Answers

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1. During inspiration, the vertical dimension of the thoracic cavity is increased due to contraction of:
a) Diaphragm
b) External intercostals
c) Scalene
d) Serratus anterior
e) Sternocleidomastoid
Correct answer: (a) Diaphragm

2. Carbon dioxide is carried in the blood in
A. Combination with the haemoglobin molecule
B. Combination with plasma proteins
C. Physical solution in plasma
D. Greater quantity in red blood cells than in plasma
E. Greater quantity as HCO3 ions than as other forms
ans
A. True
B. True
C. True
D. False
E. True

3. A shift of the oxygen dissociation curve of blood to the right
A. Occurs in the pulmonary capillaries.
B. Occurs if blood temperature rises.
C. Favors oxygen delivery to the tissues
D. Favors oxygen uptake from the lungs by alveolar capillary blood
E. Increases the P50 (the PO2 value giving 50 per cent blood oxygen saturation)
ans
A. False
B. True
C. True
D. False
E. True

4. The work of breathing increases when
A. Lung compliance increases.
B. The subject exercises.
C. The rate of breathing increases even though the minute volume stays constant.
D. The subject lies down.
E. Functional residual capacity increases.
ans
A. False
B. True
C. True
D. True
E. True

5. The compliance of the lungs and chest wall is
A. Expressed as volume change per unit change in pressure
B. Minimal during quiet breathing
C. Increased by the surface tension of the fluid lining the alveoli
D. Increased by surfactant
E. Changed by parallel displacement of the line relating lung volume to distending pressure
ans
A. True
B. False
C. False
D. True
E. False

6. Respiratory dead space
A. Saturates inspired air with water vapor before it reaches the alveoli
B. Removes all particles from inspired air before it reaches the alveoli
C. Decreases when blood catecholamine levels rise
D. Decreases during a deep inspiration
E. Decreases during a cough
ans
A. True
B. False
C. False
D. False
E. True

7. Vital capacity is
A. The volume of air expired from full inspiration to full expiration.
B. Reduced as one grows older.
C. Greater in men than in women of the same age and height
D. Related more to total body mass than to lean body mass
E. The sum of the inspiratory and expiratory reserve volumes
ans
A. True
B. True
C. True
D. False
E. False

8. In pulmonary capillary blood
A. Carbonic anhydrase in erythrocytes catalyses the formation of H and HCO3
B. Hydrogen ions dissociate from haemoglobin.
C. The rise in PO2 is of greater magnitude than the fall in PCO2
D. The oxygen content is linearly related to alveolar PO2.
E. The pH is lower than in blood in the pulmonary artery.
ans
A. False
B. True
C. True
D. False
E. False

9. Oxygen debt is
A. The amount of O2 consumed after cessation of exercise.
B. Incurred because the pulmonary capillary walls limit O2 uptake during exercise
C. Possible since skeletal muscle can function temporarily without oxygen
D. Associated with a rise in blood lactate
E. Associated with metabolic acidosis
ans
A. False
B. False
C. True
D. True
E. True

10. The CO2 dissociation curve for whole blood shows that
A. Its shape is sigmoid.
B. Blood saturates with CO2 when PCO2 exceeds normal alveolar levels.
C. Blood contains some CO2 even when the PCO2 is zero.
D. Oxygenation of the blood drives CO2 out of the blood.
E. Adding CO2 to the blood drives O2 out of the blood.
ans
A. False
B. False
C. False
D. True
E. False

11. The oxygen content of mixed venous blood is
A. Measured using blood sampled from the right atrium.
B. Increased during generalized muscular exercise
C. Increased in a warm environment
D. Increased in cyanide poisoning
E. Decreased in circulatory failure
ans
A. False
B. False
C. True
D. True
E. True

12. Bronchial asthma is likely to be relieved by
A. Stimulation of cholinergic receptors
B. Stimulation of beta adrenoceptors
C. Histamine aerosols
D. Drugs which stabilize mast cell membranes
E. Glucocorticoids
ans
A. False
B. True
C. False
D. True
E. True

13. Air in the pleural cavity (pneumothorax)
A. Allows intrapleural pressure to rise to atmospheric pressure
B. Causes the underlying lung to collapse by compressing it
C. Increases the functional residual capacity
D. Leads to a slight outward movement of the chest wall
E. Reduces vital capacity
ans
A. True
B. False
C. False
D. True
E. True

14. A raised blood pH and bicarbonate level is consistent with
A. Metabolic acidosis
B. Partly compensated respiratory alkalosis
C. A reduced PCO2
D. Chronic renal failure with a raised PCO2
E. A history of persistent vomiting of gastric contents
ans
A. False
B. False
C. False
D. False
E. True

15. A patient with partly compensated respiratory acidosis
A. Must have a raised PCO2
B. May have a reduced hydrogen ion concentration [H]
C. Must have a raised bicarbonate concentration [HCO3]
D. May have evidence of renal compensation
E. May have respiratory failure due to hypoventilation
ans
A. True
B. False
C. True
D. True
E. True

16. A patient with an uncompensated respiratory alkalosis may have
A. Been exposed to living at high altitudes
B. A reduced [H2CO3]:[HCO3] ratio
C. Neuromuscular hyperexcitability
D. An arterial pH of 7.3
E. A blood [H] of 30 nmol/liter
ans
A. False
B. True
C. True
D. False
E. True

17. In investigating a patient’s acid-base status
A. Venous rather than arterial blood should be studied.
B. Blood samples may be stored for up to 12 hours at room temperature before analysis.
C. pH can be calculated if [HCO3] and PCO2 are known.
D. Raised urinary ammonium salts suggest renal compensation for respiratory acidosis.
E. An early fall in [HCO3] suggests that the acid-base disturbance is respiratory in origin.
ans
A. False
B. False
C. True
D. True
E. False

18. Respiratory alkalosis differs from metabolic alkalosis in that the
A. Likelihood of tetany is less.
B. Urine is alkaline.
C. Arterial blood [HCO3] is normal or low.
D. Arterial blood PCO2 is reduced.
E. Reduction in cerebral blood flow is greater.
ans
A. False
B. False
C. True
D. True
E. True

19. A patient with chronic respiratory failure
A. Shows an enhanced respiratory sensitivity to inhaled carbon dioxide
B. Shows little or no respiratory response to hypoxia
C. Is likely to have a low blood bicarbonate level
D. Responds well when given 100 per cent oxygen to breathe
E. Must have been breathing oxygen-enriched air if alveolar PCO2 is 150 mmHg (20 kPa)
ans
A. False
B. False
C. False
D. False
E. True

20. Loss of pulmonary elastic tissue in ‘emphysema’ reduces
A. Physiological dead space
B. Anatomical dead space
C. Residual volume
D. Vital capacity
E. The percentage of the vital capacity expired in one second.
ans
A. False
B. True
C. False
D. True
E. True

21. Complete obstruction of a major bronchus usually results in
A. Collapse of the alveoli supplied by the bronchus.
B. A rise in local intrapleural pressure
C. An increase in physiological dead space
D. An increase in blood flow to the lung tissue supplied by the bronchus
E. Cyanosis.
ans
A. True
B. False
C. False
D. False
E. False

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