Q: Which of the following formulas correctly calculates alveolar ventilation rate (AVR)?

$$AVR = (TV - \, dead\, space) \times frequency$$

Q: According to Dalton’s law, what is the partial pressure of oxygen ($$P_{O_2$}) in $$dry atmospheric air at sea level (760 mm Hg) if oxygen makes up 20.9% of the air?

$$P_{O_2$} = 0.209 \times 760 = 159 mm Hg$$

Question 1

Which of the following best describes the relationship between intrapulmonary pressure ($$P_{pul}$$), intrapleural pressure ($$P_{ip}$$), and transpulmonary pressure during normal quiet breathing?

Accepted Answer

Transpulmonary pressure is calculated as $$P_{pul} - P_{ip}$$ and must remain positive to keep the lungs inflated.

Question 2

A patient suffers a stab wound that punctures the parietal pleura. Which of the following is the most likely immediate consequence?

Accepted Answer

Intrapleural pressure equalizes with atmospheric pressure, leading to lung collapse (pneumothorax).

Question 3

According to Boyle’s law, what happens to the pressure of a gas if the volume of its container is halved, assuming the amount of gas remains constant?

Accepted Answer

The pressure doubles.

Question 4

During inspiration, which of the following events occurs first?

Accepted Answer

Inspiratory muscles contract, increasing thoracic cavity volume.

Question 5

Which equation correctly represents the relationship between lung compliance ($$C_L$$), change in lung volume ($$\Delta V_L$$), and change in transpulmonary pressure ($$\Delta (P_{pul} - P_{ip})$$)?

Accepted Answer

$$C_L = \frac{\Delta V_L}{\Delta (P_{pul} - P_{ip})}$$

Question 6

A premature infant is diagnosed with infant respiratory distress syndrome (IRDS). What is the primary physiological problem in this condition?

Accepted Answer

Insufficient surfactant increases alveolar surface tension, causing alveolar collapse.

Question 7

Which of the following best explains why airway resistance is usually insignificant in the terminal bronchioles?

Accepted Answer

Progressive branching increases total cross-sectional area, reducing resistance.

Question 8

A patient with chronic bronchitis is likely to have which of the following changes in lung volumes and capacities?

Accepted Answer

Increased TLC and RV due to hyperinflation of the lungs.

Question 9

Which of the following formulas correctly calculates alveolar ventilation rate (AVR)?

Accepted Answer

$$AVR = (TV - \, dead\, space) 	imes frequency$$

Question 10

A patient is breathing rapidly and shallowly. Which of the following is most likely to occur regarding their alveolar ventilation rate (AVR)?

Accepted Answer

AVR decreases because a greater proportion of each breath is dead space air.

Question 11

According to Dalton’s law, what is the partial pressure of oxygen ($$P_{O_2$}) in $$dry atmospheric air at sea level (760 mm Hg) if oxygen makes up 20.9% of the air?

Accepted Answer

$$P_{O_2$} = 0.209 	imes 760 = 159 mm Hg$$

Question 12

Which of the following best explains why carbon dioxide ($$CO_2) $$diffuses in equal amounts with oxygen ($$O_2) $$across the respiratory membrane, despite a much smaller partial pressure gradient?

Accepted Answer

$$CO_2 is 20 $$times more soluble in plasma and alveolar fluid than $$O_2.$$

Question 13

A patient with emphysema has a reduced alveolar surface area. What is the most likely effect on external respiration?

Accepted Answer

Decreased rate of gas exchange due to reduced surface area.

Question 14

Which of the following changes would occur in the pulmonary arterioles in response to low alveolar $$P_{O_2$}$$?

Accepted Answer

Pulmonary arterioles constrict to redirect blood to better-ventilated alveoli.

Question 15

Which of the following is a correct calculation for vital capacity (VC) using respiratory volumes?

Accepted Answer

$$VC = TV + IRV + ERV$$

Question 16

A patient with pulmonary fibrosis has decreased lung compliance. Which of the following best describes the physiological consequence?

Accepted Answer

More energy is required to breathe due to stiff, nonelastic lung tissue.

Question 17

Which of the following best describes the effect of surfactant on alveolar surface tension?

Accepted Answer

Surfactant decreases surface tension, preventing alveolar collapse.

Question 18

During external respiration, which of the following partial pressure gradients drives oxygen from the alveoli into the blood?

Accepted Answer

$$P_{O_2$} in $$alveoli is higher than in venous blood.

Question 19

Which of the following is a real-life example of Henry’s law in clinical practice?

Accepted Answer

Using a hyperbaric oxygen chamber to treat carbon monoxide poisoning.

Respiratory Physiology: Mechanics, Pressures, and Gas Exchange

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