Q: According to Dalton’s Law, what is the partial pressure of oxygen in atmospheric air if the total atmospheric pressure is 760 mm Hg and oxygen makes up 20.9% of the air?

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

Question 1

Which of the following best describes the primary function of the respiratory system?

Accepted Answer

To exchange gases (O2 and CO2) between the air and circulating blood

Question 2

Which structure marks the transition from the conducting portion to the respiratory portion of the respiratory tract?

Accepted Answer

Terminal bronchioles

Question 3

A patient with pneumonia has fluid accumulation in the alveoli. Which part of the blood-air barrier is most directly affected, impairing gas exchange?

Accepted Answer

Simple squamous epithelium of alveoli

Question 4

Which of the following equations correctly represents Boyle’s Law as it applies to pulmonary ventilation?

Accepted Answer

$$P_1V_1 = P_2V_2$$

Question 5

Which of the following changes would most likely increase lung compliance?

Accepted Answer

Destruction of connective tissue in the lungs

Question 6

During quiet breathing, which muscles are primarily responsible for inspiration, and what percentage of air movement does each contribute?

Accepted Answer

Diaphragm (75%), external intercostals (25%)

Question 7

A person is exposed to a toxin that destroys type II pneumocytes. What is the most likely consequence?

Accepted Answer

Collapse of alveoli due to increased surface tension

Question 8

Which of the following best explains why fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin?

Accepted Answer

Fetal hemoglobin binds more O2 at lower partial pressures

Question 9

According to Dalton’s Law, what is the partial pressure of oxygen in atmospheric air if the total atmospheric pressure is 760 mm Hg and oxygen makes up 20.9% of the air?

Accepted Answer

$$	ext{Partial pressure} = 760 	imes 0.209 = 159 	ext{ mm Hg}$$

Question 10

Which of the following is the correct sequence of airflow through the respiratory tract, starting at the nose?

Accepted Answer

Nose → pharynx → larynx → trachea → bronchi → bronchioles → alveoli

Question 11

A patient is experiencing hypoventilation. What changes in blood gases and pH would you expect?

Accepted Answer

Increased CO2, decreased pH (acidosis)

Question 12

Which of the following best describes the role of carbonic anhydrase in CO2 transport?

Accepted Answer

It catalyzes the conversion of CO2 and H2O to carbonic acid, which dissociates into H+ and HCO3-

Question 13

Which of the following is NOT a function of the upper respiratory system?

Accepted Answer

Gas exchange between air and blood

Question 14

Which respiratory volume is defined as the amount of air that remains in the lungs after a maximal exhalation?

Accepted Answer

Residual volume

Question 15

Which of the following best describes the effect of a decrease in blood pH on hemoglobin’s affinity for oxygen?

Accepted Answer

Decreased affinity, more O2 released to tissues

Question 16

Which of the following is the main mechanism by which most CO2 is transported in the blood?

Accepted Answer

As bicarbonate ions in plasma

Question 17

Which respiratory center is primarily responsible for setting the basic pace of respiration?

Accepted Answer

Medullary respiratory rhythmicity center

Question 18

A patient with emphysema will have which of the following changes in their lungs?

Accepted Answer

Destruction of alveolar walls, reducing surface area for gas exchange

Question 19

Which of the following best describes the Hering-Breuer inflation reflex?

Accepted Answer

Prevents overexpansion of the lungs during inspiration

The Respiratory System: Structure, Function, and Physiology

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