Q: According to Dalton’s Law, what is the partial pressure of oxygen ($$P_{O_2$}) in $$atmospheric air at sea level if the total atmospheric pressure is 760 mm Hg and oxygen makes up 21% of the air?

$$P_{O_2$} = 760 \times 0.21 = 159.6 mm Hg$$

Question 1

Which of the following best describes the primary function of the respiratory mucosa in the conducting portion of the respiratory tract?

Accepted Answer

It traps debris and pathogens in mucus and moves them toward the pharynx via ciliary action.

Question 2

A patient with severe asthma experiences bronchoconstriction. Which of the following best explains the physiological effect on airflow?

Accepted Answer

Airway resistance increases, making it harder to move air through the bronchioles.

Question 3

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

Accepted Answer

$$P_1$$ $$V_1$$ = $$P_2$$ $$V_2$$

Question 4

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

Accepted Answer

Diaphragm and external intercostal muscles

Question 5

A blood clot blocks a branch of the pulmonary artery, causing a pulmonary embolism. What is the most likely immediate consequence for the affected lung tissue?

Accepted Answer

Permanent collapse of alveoli supplied by the blocked artery

Question 6

Which of the following best explains why surfactant is essential for normal lung function?

Accepted Answer

It reduces surface tension in the alveoli, preventing their collapse.

Question 7

According to Dalton’s Law, what is the partial pressure of oxygen ($$P_{O_2$}) in $$atmospheric air at sea level if the total atmospheric pressure is 760 mm Hg and oxygen makes up 21% of the air?

Accepted Answer

$$P_{O_2$} = 760 	imes 0.21 = 159.6 mm Hg$$

Question 8

A patient is exposed to carbon monoxide, which binds to hemoglobin with a higher affinity than oxygen. What is the most likely effect on the oxygen-hemoglobin saturation curve?

Accepted Answer

The curve shifts to the left, indicating decreased oxygen release to tissues.

Question 9

Which of the following best describes the main mechanism by which most carbon dioxide is transported in the blood?

Accepted Answer

As bicarbonate ions formed in red blood cells

Question 10

A person is holding their breath while swimming underwater. Which physiological mechanism will eventually force them to resume breathing?

Accepted Answer

Increased arterial $$P_{CO_2$}$$ detected by central chemoreceptors

Question 11

Which of the following changes would most likely increase the efficiency of gas exchange across the blood-air barrier?

Accepted Answer

Increasing the total surface area of alveoli

Question 12

Which of the following best describes the effect of a decrease in blood pH on the oxygen-hemoglobin saturation curve?

Accepted Answer

The curve shifts to the right, and hemoglobin releases more oxygen to tissues.

Question 13

Which of the following is a direct result of sympathetic activation on the bronchioles?

Accepted Answer

Bronchodilation, decreasing airway resistance

Question 14

A patient with pneumonia has fluid accumulation in the alveoli. Which of the following best explains why this impairs gas exchange?

Accepted Answer

It increases the distance for diffusion across the blood-air barrier.

Question 15

Which of the following best describes the role of the dorsal respiratory group (DRG) in the medulla oblongata?

Accepted Answer

It stimulates inspiratory muscles during quiet and forced breathing.

Question 16

Which of the following equations correctly calculates the respiratory minute volume ($$V_E$$)?

Accepted Answer

$$V_E = Tidal\ Volume 	imes Respiratory\ Rate$$

Question 17

Which of the following is a function of the paranasal sinuses in the upper respiratory system?

Accepted Answer

They moisten and warm incoming air.

Question 18

Which of the following best describes the effect of increased temperature on hemoglobin’s affinity for oxygen?

Accepted Answer

Hemoglobin releases more oxygen to tissues, shifting the saturation curve to the right.

Question 19

Which of the following is the correct sequence of airflow through the respiratory tract during inhalation?

Accepted Answer

Nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles → alveoli

Question 20

Which of the following best explains why the left lung has fewer lobes than the right lung?

Accepted Answer

The left lung is smaller to accommodate the position of the heart.

Chapter 23: The Respiratory System – Structure, Function, and Regulation

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