Q: Which of the following best describes the formula for calculating the partial pressure of a gas in a mixture according to Dalton’s Law?

Partial pressure of gas = Total pressure \times percentage of gas

Q: A patient has a tidal volume (TV) of 500 mL, an inspiratory reserve volume (IRV) of 3100 mL, and an expiratory reserve volume (ERV) of 1200 mL. What is the patient’s vital capacity (VC)?

VC = TV + IRV + ERV = 500 + 3100 + 1200 = 4800 \text{ mL}

Q: If the atmospheric pressure at sea level is 760 mm Hg and oxygen makes up 20.9% of the air, what is the partial pressure of oxygen?

$$PO_2 = 760$$ \times 0.209 = 159 \text{ mm Hg}$$

Question 1

Which of the following best describes the formula for calculating the partial pressure of a gas in a mixture according to Dalton’s Law?

Accepted Answer

Partial pressure of gas = Total pressure 	imes percentage of gas

Question 2

A patient has a tidal volume (TV) of 500 mL, an inspiratory reserve volume (IRV) of 3100 mL, and an expiratory reserve volume (ERV) of 1200 mL. What is the patient’s vital capacity (VC)?

Accepted Answer

VC = TV + IRV + ERV = 500 + 3100 + 1200 = 4800 	ext{ mL}

Question 3

According to Henry’s Law, which factor will increase the amount of oxygen dissolved in blood?

Accepted Answer

Increasing the partial pressure of oxygen in the alveoli

Question 4

During external respiration, which direction does oxygen move and why?

Accepted Answer

Oxygen moves from alveoli (PO2 = 104 mm Hg) to blood (PO2 = 40 mm Hg) due to the partial pressure gradient

Question 5

If the atmospheric pressure at sea level is 760 mm Hg and oxygen makes up 20.9% of the air, what is the partial pressure of oxygen?

Accepted Answer

$$PO_2 = 760$$ 	imes 0.209 = 159 	ext{ mm Hg}$$

Question 6

Which respiratory volume is defined as the amount of air left in the lungs after a forced expiration?

Accepted Answer

Residual volume (RV)

Question 7

A person’s total lung capacity (TLC) is calculated using the following volumes: TV = 500 mL, IRV = 3100 mL, ERV = 1200 mL, RV = 1200 mL. What is the TLC?

Accepted Answer

$$TLC = TV + IRV + ERV + RV = 500 + 3100 + 1200 + 1200 = 6000 	ext{ mL}$$

Question 8

Which of the following best explains why CO2 diffuses from blood into alveoli during external respiration?

Accepted Answer

CO2 moves down its partial pressure gradient from blood (PCO2 = 45 mm Hg) to alveoli (PCO2 = 40 mm Hg)

Question 9

Which of the following is NOT a factor that influences external respiration?

Accepted Answer

Amount of hemoglobin in the blood

Question 10

During tissue gas exchange, what is the partial pressure gradient for oxygen?

Accepted Answer

Oxygen diffuses from blood (PO2 = 95 mm Hg) to systemic cells (PO2 = 40 mm Hg)

Question 11

Which of the following statements about ventilation-perfusion coupling is correct?

Accepted Answer

High alveolar PO2 causes pulmonary arterioles to dilate, increasing perfusion

Question 12

If a person’s ERV is 1200 mL and RV is 1200 mL, what is their functional residual capacity (FRC)?

Accepted Answer

$$FRC = ERV + RV = 1200 + 1200 = 2400 	ext{ mL}$$

Question 13

Which of the following best describes the effect of temperature on oxygen release from hemoglobin?

Accepted Answer

As temperature increases, more oxygen is released from hemoglobin

Question 14

What is the definition of inspiratory capacity (IC)?

Accepted Answer

IC = TV + IRV; total ability to inspire

Question 15

Which gas is most soluble in water according to Henry’s Law?

Accepted Answer

CO2

Question 16

A person at high altitude (10,000 ft) has an atmospheric pressure of 523 mm Hg. What is the partial pressure of oxygen if O2 is 20.9% of the air?

Accepted Answer

$$PO_2 = 523$$ 	imes 0.209 = 109.307 	ext{ mm Hg}$$

Question 17

Which of the following is a consequence of reduced ventilation in alveoli?

Accepted Answer

Pulmonary arterioles constrict, reducing perfusion to match decreased ventilation

Question 18

Which respiratory volume is a measure of lung compliance?

Accepted Answer

Inspiratory reserve volume (IRV)

Respiratory System: Gas Exchange, Volumes, and Capacities 23-2

Study Guide - Practice Questions

Study Guide - Flashcards