Q: A climber ascends to 10,000 feet, where atmospheric pressure is 523 mm Hg. What is the partial pressure of oxygen ($$P_{O_2$}) if $$oxygen makes up 20.9% of air?

$$P_{O_2$} = 0.209 \times 523 = 109.3 mm Hg$$

Question 1

A scuba diver ascends too quickly, causing nitrogen to rapidly come out of solution in the blood. Which gas law best explains why this occurs?

Accepted Answer

Henry’s Law

Question 2

During quiet inspiration, which of the following events occurs FIRST?

Accepted Answer

Diaphragm contracts and moves downward

Question 3

A patient with pneumonia develops pulmonary edema. How does this affect gas exchange?

Accepted Answer

It increases the thickness of the respiratory membrane, slowing O₂ diffusion

Question 4

Which of the following best describes the relationship between pressure and volume in the lungs during breathing, according to Boyle’s Law?

Accepted Answer

Pressure and volume are inversely proportional: $$P_1V_1 = P_2V_2$$

Question 5

A patient suffers a puncture wound to the chest, causing air to enter the pleural cavity. What is the most likely consequence?

Accepted Answer

Increased intrapleural pressure, leading to lung collapse (pneumothorax)

Question 6

Which of the following lung volumes represents the amount of air remaining in the lungs after a maximal forced expiration?

Accepted Answer

Residual Volume (RV)

Question 7

Dalton’s Law states that the total pressure of a gas mixture is:

Accepted Answer

The sum of the partial pressures of each gas: $$P_{total} = P_1$ + P_2$ + ... + P_n$$

Question 8

Which of the following would most likely increase airway resistance and decrease airflow?

Accepted Answer

Constriction of bronchioles due to asthma

Question 9

A patient with emphysema has a reduced surface area for gas exchange. What is the most likely result?

Accepted Answer

Chronic hypoxia and hypercapnia

Question 10

Which of the following best describes the effect of pulmonary surfactant?

Accepted Answer

Decreases surface tension, preventing alveolar collapse

Question 11

A climber ascends to 10,000 feet, where atmospheric pressure is 523 mm Hg. What is the partial pressure of oxygen ($$P_{O_2$}) if $$oxygen makes up 20.9% of air?

Accepted Answer

$$P_{O_2$} = 0.209 	imes 523 = 109.3 mm Hg$$

Question 12

Which of the following scenarios would cause pulmonary vasoconstriction?

Accepted Answer

Low alveolar PO₂ due to airway obstruction

Question 13

Which of the following is TRUE regarding the mechanics of forced expiration?

Accepted Answer

It involves contraction of abdominal muscles and internal intercostals

Question 14

If a patient’s spirometry shows a decreased Forced Vital Capacity (FVC), which condition is most likely present?

Accepted Answer

Obstructive or restrictive lung disease

Question 15

Which of the following best explains why CO₂ diffuses nearly as rapidly as O₂ across the respiratory membrane, despite a much smaller pressure gradient?

Accepted Answer

CO₂ is much more soluble in blood than O₂

Question 16

Which of the following would DECREASE the efficiency of gas exchange in the lungs?

Accepted Answer

Pulmonary edema increasing membrane thickness

Question 17

Which equation correctly represents Boyle’s Law as it applies to pulmonary ventilation?

Accepted Answer

$$P_1V_1 = P_2V_2$$

Question 18

Which of the following best describes the effect of low thoracic wall compliance?

Accepted Answer

Increased effort required for ventilation

Question 19

A patient is recovering from exercise. Ventilation remains high, but cardiac output is declining. What is the immediate effect on V/Q matching?

Accepted Answer

Ventilation exceeds perfusion (V \u003e Q) in some alveoli

(2/19_A+P) Pulmonary Ventilation and Gas Exchange: Mechanics, Laws, and Clinical Relevance

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