Q: A patient is breathing air with 5.2% CO$$_2. $$Given a total air pressure of 760 mm Hg, what is the partial pressure of CO$$_2$$?

$$P_{CO_2$} = 0.052 \times 760 = 39.52 mm Hg$$

Question 1

Which of the following best describes the process of external respiration?

Accepted Answer

The exchange of gases between the alveoli and the blood.

Question 2

During quiet breathing, which of the following statements is correct regarding the use of muscle force?

Accepted Answer

Muscle force is used for inspiration but not expiration.

Question 3

Which pressure is most important in keeping the lungs from collapsing?

Accepted Answer

Intrapleural pressure

Question 4

A patient develops a pneumothorax (air in the pleural cavity). Which pressure relationship is disrupted, leading to lung collapse?

Accepted Answer

Intrapleural pressure equals atmospheric pressure.

Question 5

According to Boyle's Law, what happens to the pressure of a gas if the volume of its container increases?

Accepted Answer

The pressure decreases.

Question 6

At the end of inspiration, the intrapulmonary pressure is equal to:

Accepted Answer

Atmospheric pressure

Question 7

Which muscle is primarily responsible for inspiration during quiet breathing?

Accepted Answer

Diaphragm

Question 8

Which lung volume is the hardest to measure without advanced instrumentation?

Accepted Answer

Residual volume (RV)

Question 9

Which of the following best predicts how likely someone is to blow out all their birthday candles in a single breath?

Accepted Answer

Vital Capacity (VC)

Question 10

Dalton’s Law states that the total pressure of a gas mixture is equal to:

Accepted Answer

The sum of the partial pressures of the individual gases.

Question 11

Given two gas mixtures separated by a membrane, Gas A contains 40% nitrogen at a partial pressure of 200 mm Hg, and Gas B contains 80% nitrogen at a partial pressure of 200 mm Hg. In which direction will nitrogen move?

Accepted Answer

No net movement because the partial pressure of nitrogen is equal in both gases.

Question 12

According to Henry’s Law, the amount of a gas that will dissolve in a liquid is determined by:

Accepted Answer

The partial pressure of the gas and its solubility in the liquid.

Question 13

Which of the following best explains why the partial pressure of oxygen in the alveoli is lower than in the atmosphere?

Accepted Answer

Oxygen is diluted by water vapor and carbon dioxide in the alveoli.

Question 14

Which gradient most directly determines the direction that oxygen and carbon dioxide molecules will move between the air in the alveoli and the blood?

Accepted Answer

The pressure gradient between alveolar air and the blood plasma.

Question 15

A patient is breathing air with 5.2% CO$$_2. $$Given a total air pressure of 760 mm Hg, what is the partial pressure of CO$$_2$$?

Accepted Answer

$$P_{CO_2$} = 0.052 	imes 760 = 39.52 mm Hg$$

Question 16

Which of the following statements is correct regarding the movement of gases during external and internal respiration?

Accepted Answer

CO$$_2$$ always moves from the area of highest partial pressure to the area of lowest partial pressure.

Question 17

Which of the following best describes the effect of hyperventilation on the partial pressures of O$$_2$$ and CO$$_2 in $$the alveoli?

Accepted Answer

Alveolar O$$_2$$ increases, alveolar CO$$_2$$ decreases.

Question 18

Which of the following is the correct formula for calculating the partial pressure of a gas in a mixture?

Accepted Answer

$$P_{gas} = 	ext{Fraction of gas} 	imes 	ext{Total pressure}$$

Question 19

Which of the following best explains why a person with COPD has an increased residual volume?

Accepted Answer

COPD decreases the elasticity of the lungs, trapping more air in the lungs after expiration.

Study Guide: Human Anatomy & Physiology – The Respiratory System (ANP)

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