RESPIRATORY SYSTEM

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RESPIRATORY SYSTEM

Physiology

1. The physiological dead space:

1 point

a) Is exactly equal to the anatomic dead space in normal people

b) Increases during exercise

c) Is measured by single breath nitrogen analysis

d) Is higher in elderly than young adults

e) Is the same as the physiological shunt

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2. A high alveolo-arterial PO2 difference most likely results from:

1 point

a) Low fractional concentration of O2 in the inspired air

b) Hypoventilation

c) Arteriovenous shunt

d) Pulmonary edema

e) Polycythemia

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3. At 33 feet under water the ambient pressure is:

0 points

a) Two atmospheres

b) One and a half atmosphere

c) 33 pounds per square inch

d) Same as the pressure in a tunnel 33 feet below sea level

e) Half the pressure 33 feet above sea level

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4. Which of the following combinations are typical findings in compensated respiratory alkalosis:

1 point

a) Low PaCO2, low bicarbonate level and normal pH

b) Low PaCO2, normal bicarbonate level and high pH

c) Low PaCO2, low bicarbonate level and high pH

d) Low PaCO2, normal bicarbonate level and normal pH

e) Low PaCO2, high bicarbonate level and high pH

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5. The partial pressure of oxygen in the alveoli is expected to be least affected by:

1 point

a) Fractional concentration of O2 in ispired air

b) Respiratory quotient

c) PCO2 in alveoli

d) Hemoglobin concentration

e) Barometric pressure

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6. A veno-arterial shunt is likely to:

1 point

a) Decrease the cardiac output

b) Increase the pulse pressure

c) Increase venous return

d) Decrease PaO2

e) Increase the peripheral vascular resistance

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7. The arterio-venous difference of O2 is highest across:

1 point

a) Liver

b) Kidney

c) Cardiac muscle

d) Skin

e) Brain

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8. In a patient, hypoventilation is most likely if:

1 point

a) PaO2 is low

b) pH of arterial blood is low

c) PaCO2 is high

d) O2 in arterial blood is low

e) PCO2 of expired air is high

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9. A decrease in the recoil force of the lung is likely to:

1 point

a) Decrease total lung capacity

b) Increase vital capacity

c) Increase functional residual capacity

d) Decrease the residual volume

e) Decrease compliance of the lung

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10. Central chemoreceptors differ from chemoreceptors in that they:

1 point

a) Respond to changes in PaCO2

b) Respond to changes in pH

c) Do not respond to changes in PO2

d) Become more sensitive to CO2 with chronic exposure

e) They are less sensitive to changes in PaCO2 than pH

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11. Surfactant:

1 point

a) Helps to equalize pressure within interconnected alveoli

b) Reduces surface tension more effectively as alveolus becomes smaller

c) Increases lung compliance

d) Increases the slope of the pressure-volume curve

e) All of the above

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12. In a normal adult man, breathing 100% oxygen:

1 point

a) Is likely to double O2 in arterial blood

b) Is likely to reduce alveolar PCO2

c) Is likely to raise PO2 in venous blood to about 200 mmHg

d) Is likely to raise arterial PO2 to about 660 mmHg

e) Increases the affinity of hemoglobin to oxygen

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13. At the end of maximum inspiration:

1 point

a) Intra-alveolar pressure is zero

b) Intra-pleural pressure is zero

c) Recoil force of the chest is greater than the recoil force of the lung

d) Surface tension is lowest

e) Average alveolar PO2 is lower than at the end of maximum expiration

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14. Compliance of the lung:

1 point

a) Is higher in small children than in adults

b) Is about 500 ml/cm H2O

c) Is normally twice the compliance of the chest

d) Is higher in elderly than young adults

e) Is decreased in emphysematous changes

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15. The ventilatory response to hypoxia:

1 point

a) Is independent of arterial PCO2

b) Is mediated by the central chemoreceptors

c) Decreases gradually with time

d) Is largely mediated by the aortic bodies in humans

e) None of the above

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16. Compared to normal arterial blood, normal mixed venous blood has:

1 point

a) Higher PO2, lower PCO2 and higher pH

b) Lower PO2, higher PCO2 and higher pH

c) Lower PO2, higher PCO2 and lower pH

d) Lower PO2, lower PCO2 and higher pH

e) Higher PO2, lower PCO2 and lower pH

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