Q: Calculate the transpulmonary pressure if the intrapulmonary pressure is 0 mm Hg and the intrapleural pressure is -4 mm Hg.

$$P_{tp} = P_{pul} - P_{ip} = 0 - (-4) = 4 \text{ mm Hg}$$

Question 1

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

Accepted Answer

Pressure and volume are inversely proportional; as volume increases, pressure decreases.

Question 2

A patient suffers a puncture wound to the chest wall, resulting in air entering the pleural cavity. Which condition is most likely to develop, and what is the underlying pressure change?

Accepted Answer

Pneumothorax; intrapleural pressure becomes equal to atmospheric pressure.

Question 3

During inspiration, which of the following events occurs to facilitate airflow into the lungs?

Accepted Answer

The diaphragm contracts, increasing thoracic volume and decreasing intrapulmonary pressure.

Question 4

Calculate the transpulmonary pressure if the intrapulmonary pressure is 0 mm Hg and the intrapleural pressure is -4 mm Hg.

Accepted Answer

$$P_{tp} = P_{pul} - P_{ip} = 0 - (-4) = 4 	ext{ mm Hg}$$

Question 5

Which of the following would most likely cause a lung to collapse?

Accepted Answer

Transpulmonary pressure becomes zero because intrapleural pressure equals intrapulmonary pressure.

Question 6

A patient is breathing pure oxygen at 2.5 atmospheres for several hours. What is the most likely physiological consequence?

Accepted Answer

Oxygen toxicity due to generation of free radicals, leading to CNS disturbances.

Question 7

Which equation correctly represents the formation of bicarbonate ions from carbon dioxide in the blood?

Accepted Answer

$$CO_2 + H_2O$$ \rightarrow H_2CO_3 \rightarrow H^+ + $$HCO_3$$^-$$

Question 8

Which of the following best explains why CO$$_2$$ diffuses in equal amounts with O$$_2$$ across the respiratory membrane, despite a smaller partial pressure gradient?

Accepted Answer

CO$$_2 is 20 $$times more soluble in plasma and alveolar fluid than O$$_2.$$

Question 9

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

Accepted Answer

Increased TLC, FRC, and RV due to hyperinflation of the lungs.

Question 10

Which of the following is a consequence of hyperventilation?

Accepted Answer

Decreased blood CO$$_2$$ levels (hypocapnia), leading to cerebral vasoconstriction and dizziness.

Question 11

Which of the following best describes the effect of increased temperature on gas solubility in blood?

Accepted Answer

As temperature rises, gas solubility decreases.

Question 12

A patient with pulmonary fibrosis is likely to have which of the following changes in lung compliance?

Accepted Answer

Decreased lung compliance due to fibrous tissue buildup.

Question 13

Which of the following mechanisms helps match ventilation and perfusion in the lungs?

Accepted Answer

Local changes in arteriolar and bronchiolar diameter in response to O$$_2$$ and CO$$_2$$ levels.

Question 14

Which of the following is the correct formula for calculating vital capacity (VC)?

Accepted Answer

$$VC = ERV + TV + IRV$$

Question 15

A patient with an obstructive pulmonary disorder is likely to have which of the following findings on spirometry?

Accepted Answer

FEV$$_1 is $$less than 80% of FVC in the first second.

Question 16

Which of the following best explains the chloride shift in systemic capillaries?

Accepted Answer

As HCO$$_3^-$$ diffuses out of RBCs into plasma, Cl$$^-$$ moves into RBCs to maintain electrical neutrality.

Question 17

Which of the following conditions is characterized by impaired or blocked circulation leading to inadequate oxygen delivery to tissues?

Accepted Answer

Ischemic hypoxia

Question 18

Which of the following is the primary function of surfactant in the alveoli?

Accepted Answer

Reduces surface tension of alveolar fluid and discourages alveolar collapse.

Question 19

Which of the following best describes the effect of slow, shallow breathing on blood pH?

Accepted Answer

Increases CO$$_2 in $$blood, resulting in a drop in pH (acidosis).

Pressure Relationships and Pulmonary Ventilation in the Thoracic Cavity

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