Question 1

Which law explains why an increase in the volume of the thoracic cavity during inspiration leads to a decrease in intrapulmonary pressure, allowing air to flow into the lungs?

Accepted Answer

Boyle's law

Question 2

During forced expiration, which muscles are primarily involved in decreasing the volume of the thoracic cavity?

Accepted Answer

Internal intercostals and abdominal muscles

Question 3

What is the main function of pulmonary surfactant, and which cells secrete it?

Accepted Answer

Reduces surface tension; secreted by Type II alveolar cells

Question 4

Which anatomical feature distinguishes the right lung from the left lung?

Accepted Answer

The right lung has three lobes, while the left lung has two lobes and a cardiac notch.

Question 5

Which mechanism is primarily responsible for preventing dust and debris from reaching the alveoli?

Accepted Answer

Ciliated epithelial cells and mucus trap and move particles upward toward the pharynx.

Question 6

What maintains the patency (openness) of the trachea during breathing?

Accepted Answer

C-shaped rings of hyaline cartilage

Question 7

According to Dalton's law, the total pressure of a gas mixture is equal to:

Accepted Answer

The sum of the partial pressures of each individual gas in the mixture

Question 8

How is the majority of oxygen transported in the blood?

Accepted Answer

Bound to hemoglobin within red blood cells

Question 9

Which equation best represents Henry's law as it applies to gas exchange in the lungs?

Accepted Answer

$$C = k \cdot P$$

Question 10

What is the most powerful stimulus for breathing under normal conditions?

Accepted Answer

Increased CO$$_2$$ levels in the blood

Question 11

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 O$$_2$$ unloading in tissues.

Question 12

Which mechanism accounts for the bulk of CO$$_2$$ transport in the blood?

Accepted Answer

As bicarbonate ions ($$HCO_3$$^-$$) in plasma

Question 13

Which term describes the exchange of gases between systemic capillaries and body tissues?

Accepted Answer

Internal respiration

Question 14

Ventilation-perfusion coupling ensures that:

Accepted Answer

Areas of the lung receiving more air also receive more blood flow for optimal gas exchange.

Question 15

Which two types of cells make up the alveoli?

Accepted Answer

Type I alveolar cells (simple squamous) and Type II alveolar cells (surfactant-secreting)

Question 16

Which structures form the respiratory membrane where gas exchange occurs?

Accepted Answer

Alveolar epithelium, fused basement membrane, and capillary endothelium

Question 17

A patient with impaired surfactant production is likely to experience which physiological consequence?

Accepted Answer

Increased alveolar surface tension leading to alveolar collapse (atelectasis)

Question 18

During quiet inspiration, which process occurs to allow air to enter the lungs?

Accepted Answer

The diaphragm contracts, increasing thoracic volume and decreasing intrapulmonary pressure below atmospheric pressure.

Question 19

Which equation best represents Boyle's law as it applies to lung mechanics?

Accepted Answer

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

Question 20

A person inhales deeply and holds their breath. Which pressure changes occur in the lungs during this process?

Accepted Answer

Intrapulmonary pressure decreases below atmospheric pressure during inhalation, then equalizes when breath is held.

Respiratory System: Structure, Function, and Gas Exchange

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