Question 1

Which type of hypoxia is most likely to occur in a patient with severe anemia, and why?

Accepted Answer

Anemic hypoxia, because the blood's oxygen-carrying capacity is decreased due to low hemoglobin.

Question 2

A climber at high altitude experiences shortness of breath and low arterial $$P_{O_2$}. $$Which type of hypoxia is this, and what is the primary cause?

Accepted Answer

Hypoxic hypoxia; due to low environmental oxygen.

Question 3

Which law explains why increasing the volume of the thoracic cavity during inspiration decreases alveolar pressure and draws air into the lungs?

Accepted Answer

Boyle's Law: $$P_1$$ $$V_1$$ = $$P_2$$ $$V_2$$

Question 4

A patient suffers a puncture wound to the chest, resulting in a collapsed lung. Which of the following best explains the physiological mechanism behind this condition?

Accepted Answer

The intrapleural pressure becomes equal to atmospheric pressure, eliminating the vacuum that keeps the lung inflated.

Question 5

According to the Law of Laplace, what happens to the pressure inside a smaller alveolus compared to a larger one, assuming equal surface tension?

Accepted Answer

The pressure is higher in the smaller alveolus because $$P = \frac{2T}{r}$$ and $$r is $$smaller.

Question 6

Which of the following best describes the role of pulmonary surfactant in the alveoli?

Accepted Answer

It decreases surface tension, especially in smaller alveoli, preventing collapse and equalizing pressure.

Question 7

A newborn is diagnosed with infant respiratory distress syndrome (IRDS). Which of the following best explains the underlying cause?

Accepted Answer

Low surfactant production increases alveolar surface tension, causing alveolar collapse.

Question 8

During quiet breathing, which muscle is primarily responsible for inspiration, and what is its action?

Accepted Answer

Diaphragm; contracts and moves downward to increase thoracic volume.

Question 9

Which of the following best explains why the partial pressure of oxygen in the alveoli ($$P_{O_2$}) is $$significantly lower than in atmospheric air?

Accepted Answer

Mixing of fresh atmospheric air with stale air in the anatomical dead space reduces alveolar $$P_{O_2$}.$$

Question 10

A patient with chronic obstructive pulmonary disease (COPD) is likely to have which of the following spirometry findings?

Accepted Answer

Decreased inspiratory capacity and increased residual volume.

Question 11

Which of the following equations correctly calculates alveolar ventilation rate ($$V_A) in a $$healthy adult?

Accepted Answer

$$V_A = (Tidal\ Volume - Dead\ Space) 	imes Respiratory\ Rate$$

Question 12

Which of the following best describes the difference between obstructive and restrictive pulmonary pathologies?

Accepted Answer

Obstructive pathologies primarily impair expiration, while restrictive pathologies impair inspiration.

Question 13

If a person’s tidal volume is 500 mL, anatomical dead space is 150 mL, and respiratory rate is 12 breaths per minute, what is their alveolar ventilation per minute?

Accepted Answer

$$(500 - 150) 	imes 12 = 4200\ mL/min$$

Question 14

Which of the following is true regarding the pressures in the lung at the end of inspiration during quiet breathing?

Accepted Answer

Alveolar pressure is equal to atmospheric pressure.

Question 15

Which muscle group is primarily recruited during forced expiration, such as blowing out candles?

Accepted Answer

Internal intercostals and rectus abdominis.

Question 16

A patient is poisoned with cyanide, which blocks the electron transport chain. What type of hypoxia will result?

Accepted Answer

Histotoxic hypoxia.

Question 17

Which of the following best explains why lung compliance is reduced in diseases like emphysema or black lung?

Accepted Answer

Elastic fibers are destroyed or stiffened, making the lungs less able to expand.

Question 18

Which cell type is responsible for producing pulmonary surfactant in the alveoli?

Accepted Answer

Type II alveolar cells.

Question 19

Which of the following best describes the effect of anatomical dead space on gas exchange in the lungs?

Accepted Answer

It reduces the proportion of tidal volume that consists of fresh air, lowering alveolar $$P_{O_2$}.$$

Respiratory System: Mechanics, Gas Exchange, and Pathology

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