Q: A patient has a tidal volume of 500 mL and a respiratory rate of 12 breaths per minute. What is their minute ventilation ($$V_E$$)?

$$V_E = 500 \times 12 = 6000 mL/$$min

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

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

Question 1

According to Boyle's Law, what will happen to the pressure of air in the lungs if the volume of the thoracic cavity increases during inspiration, assuming temperature remains constant?

Accepted Answer

The pressure will decrease because the gas molecules have more space to move.

Question 2

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

Accepted Answer

It decreases the surface tension of alveolar fluid, preventing alveolar collapse during expiration.

Question 3

A patient has a tidal volume of 500 mL and a respiratory rate of 12 breaths per minute. What is their minute ventilation ($$V_E$$)?

Accepted Answer

$$V_E = 500 	imes 12 = 6000 mL/$$min

Question 4

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

Accepted Answer

Constriction of bronchioles due to inhaled irritants

Question 5

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

Accepted Answer

Diaphragm and external intercostals

Question 6

If the intrapleural pressure becomes equal to atmospheric pressure, what is the most likely consequence?

Accepted Answer

The lungs will collapse because the negative pressure holding them open is lost.

Question 7

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

Accepted Answer

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

Question 8

Which of the following best describes the Haldane effect?

Accepted Answer

The increased ability of deoxygenated hemoglobin to bind and carry carbon dioxide.

Question 9

A person is exposed to a chemical that inhibits the production of surfactant in the lungs. Which of the following is the most likely physiological consequence?

Accepted Answer

Increased risk of alveolar collapse (atelectasis) during expiration

Question 10

Which of the following statements about the relationship between $$CO_2$$, $$H_2O$$, and $$HCO_3$$^-$$ in the blood is correct?

Accepted Answer

$$CO_2$$ combines with $$H_2O to $$form $$HCO_3$$^-$$ and H$$^+$$, a reaction catalyzed by carbonic anhydrase.

Question 11

Which of the following would most likely decrease lung compliance?

Accepted Answer

Fibrosis (scarring) of lung tissue

Question 12

A patient is experiencing an asthma attack, causing bronchoconstriction. Which physical factor influencing pulmonary ventilation is most directly affected?

Accepted Answer

Airway resistance

Question 13

Which of the following best describes the Bohr effect?

Accepted Answer

Increased $$CO_2$$ and decreased pH reduce hemoglobin's affinity for $$O_2$$, promoting oxygen release in tissues.

Question 14

Which of the following is the correct sequence of airflow from the trachea to the alveoli?

Accepted Answer

Trachea $$\rightarrow$$ primary bronchi $$\rightarrow$$ secondary bronchi $$\rightarrow$$ tertiary bronchi $$\rightarrow$$ bronchioles $$\rightarrow$$ terminal bronchioles $$\rightarrow$$ respiratory bronchioles $$\rightarrow$$ alveolar ducts $$\rightarrow$$ alveolar sacs

Question 15

If a person has a total lung capacity (TLC) of 6000 mL, a tidal volume (TV) of 500 mL, an inspiratory reserve volume (IRV) of 3000 mL, and an expiratory reserve volume (ERV) of 1200 mL, what is their residual volume (RV)? Use the formula $$TLC = TV + IRV + ERV + RV.$$

Accepted Answer

$$RV = 6000 - (500 + 3000 + 1200) = 1300 mL$$

Question 16

Which of the following best explains why the partial pressure of oxygen in alveolar air is lower than in atmospheric air?

Accepted Answer

Oxygen is diluted by the addition of water vapor and mixing with residual air in the lungs.

Question 17

Which of the following would most likely result in a rightward shift of the oxygen-hemoglobin dissociation curve?

Accepted Answer

Increased $$CO_2$$, increased temperature, and decreased pH

Question 18

Which of the following is the primary factor that determines the direction of gas movement across the respiratory membrane?

Accepted Answer

The partial pressure gradient of the gas

Question 19

A patient with pulmonary fibrosis has a thickened respiratory membrane. What is the most likely effect on gas exchange?

Accepted Answer

Decreased rate of gas exchange due to increased diffusion distance

Chapter 22: The Respiratory System – Structure, Function, and Physiology

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