Question 1

Which of the following best describes the function of the cilia found in the respiratory epithelium?

Accepted Answer

They move mucus and trapped particles toward the pharynx for removal.

Question 2

A patient with emphysema has increased lung compliance. What is the physiological consequence of this change?

Accepted Answer

The lungs inflate easily but have reduced elastic recoil, making exhalation less effective.

Question 3

According to Boyle’s Law, what happens to the pressure of a gas in a closed container if the volume of the container increases?

Accepted Answer

The pressure decreases inversely.

Question 4

During quiet inhalation, which muscles are primarily responsible for increasing the volume of the thoracic cavity?

Accepted Answer

Diaphragm and external intercostals

Question 5

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

Accepted Answer

Insufficient production of surfactant increases alveolar surface tension, leading to collapse.

Question 6

Which equation correctly represents the calculation of the partial pressure of oxygen ($$PO_2) in $$atmospheric air at sea level (21% O2, total pressure 760 mmHg)?

Accepted Answer

$$PO_2 = 0.21$$ 	imes 760$$

Question 7

A diver ascends too quickly after a deep dive. According to Henry’s Law, what is the most likely physiological consequence?

Accepted Answer

Nitrogen will form gas bubbles in the blood, leading to decompression sickness.

Question 8

Which of the following best describes the direction of gas movement during external (pulmonary) respiration?

Accepted Answer

Oxygen moves from alveolar air into pulmonary capillary blood; carbon dioxide moves from blood into alveolar air.

Question 9

Which factor would most likely decrease the rate of gas exchange across the respiratory membrane?

Accepted Answer

Fluid accumulation in the interstitial space

Question 10

Which of the following statements about the transport of carbon dioxide in the blood is correct?

Accepted Answer

Most CO2 is transported as bicarbonate ions ($$HCO_3$$^-$$) in plasma.

Question 11

A person is experiencing an asthma attack, which causes bronchoconstriction. According to the equation $$F = \frac{P}{R}$$, what happens to airflow (F) if airway resistance (R) increases and pressure difference (P) remains constant?

Accepted Answer

Airflow decreases.

Question 12

Which of the following would shift the oxygen-hemoglobin dissociation curve to the right, promoting oxygen unloading at the tissues?

Accepted Answer

Increased acidity (lower pH)

Question 13

Which structure is the final and primary site of gas exchange in the respiratory system?

Accepted Answer

Alveoli

Question 14

A patient with pulmonary fibrosis has thickened alveolar walls. Which aspect of gas exchange is most directly affected?

Accepted Answer

Diffusion distance

Question 15

Which of the following best explains why nitrogen does not significantly exchange with blood at sea level, despite its high partial pressure in the atmosphere?

Accepted Answer

Nitrogen is not soluble in blood at sea level.

Question 16

During forceful exhalation, which muscles are recruited in addition to those used during quiet breathing?

Accepted Answer

Internal intercostals and abdominal muscles

Question 17

If atmospheric pressure at the summit of a mountain is 520 mmHg, what is the partial pressure of oxygen ($$PO_2) if $$oxygen makes up 21% of the air?

Accepted Answer

$$PO_2 = 0.21$$ 	imes 520 = 109.2$$ mmHg

Question 18

Which of the following is a function of the pleural membrane?

Accepted Answer

It mechanically couples the lungs to the thoracic wall, allowing both layers to move together.

Question 19

Which of the following best describes the conducting zone of the respiratory system?

Accepted Answer

It includes the nose, pharynx, larynx, trachea, bronchi, and terminal bronchioles, and brings air to the site of external respiration.

Question 20

A diver uses a long hose to breathe underwater without SCUBA equipment. What happens to her alveolar ventilation and why?

Accepted Answer

Alveolar ventilation decreases because the dead space in the hose increases, reducing the amount of fresh air reaching the alveoli.

The Respiratory System: Structure, Function, and Physiology

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