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

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

Question 1

Which of the following best describes the function of the 'mucus escalator' in the respiratory tract?

Accepted Answer

It moves mucus and trapped particles upward toward the pharynx via ciliary action.

Question 2

A patient inhales cold, dry air through the nose. Which anatomical features are primarily responsible for warming and humidifying this air before it reaches the lungs?

Accepted Answer

The nasal conchae and respiratory mucosa

Question 3

Which of the following correctly matches the region of the pharynx with its epithelial lining?

Accepted Answer

Nasopharynx: pseudostratified ciliated columnar epithelium

Question 4

During external respiration, an oxygen molecule must pass through several layers to reach the blood. Which of the following correctly lists the order of these layers from alveolar air to blood plasma?

Accepted Answer

Alveolar epithelium → fused basement membrane → capillary endothelium

Question 5

Which statement best explains Boyle’s Law and its relevance to pulmonary ventilation?

Accepted Answer

As the volume of the thoracic cavity increases, the pressure inside the lungs decreases, causing air to flow in. $$P_1$$ $$V_1$$ = $$P_2$$ $$V_2$$

Question 6

A scuba diver ascends rapidly to the surface, causing dissolved nitrogen to come out of solution in the blood. Which law best explains this phenomenon?

Accepted Answer

Henry’s Law: $$C = kP$$

Question 7

Which of the following best describes the difference between the right and left lungs?

Accepted Answer

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

Question 8

Which of the following best defines 'vital capacity'?

Accepted Answer

The maximum amount of air that can be exhaled after a maximal inhalation. $$VC = TV + IRV + ERV$$

Question 9

A patient is experiencing forced exhalation. Which muscles are primarily involved in this process?

Accepted Answer

Internal intercostals and abdominal muscles

Question 10

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

Accepted Answer

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

Question 11

Which of the following best explains why a can of soda foams when opened after being shaken, according to Henry’s Law?

Accepted Answer

The partial pressure of carbon dioxide above the liquid decreases rapidly, reducing its solubility and causing gas to come out of solution. $$C = kP$$

Question 12

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

Accepted Answer

Production of red blood cells

Question 13

During external respiration, which direction do oxygen and carbon dioxide move?

Accepted Answer

Oxygen moves from alveoli to blood; carbon dioxide moves from blood to alveoli.

Question 14

Which of the following best describes how a decrease in blood pH affects hemoglobin (Hb) saturation?

Accepted Answer

A decrease in pH decreases Hb’s affinity for oxygen, resulting in lower saturation at a given $$P_{O_2$}.$$

Question 15

Which of the following is the primary way carbon dioxide is transported in the blood?

Accepted Answer

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

Question 16

Which chemical reaction occurs in red blood cells to produce bicarbonate ions for carbon dioxide transport?

Accepted Answer

$$CO_2 + H_2O$$ \rightarrow H_2CO_3 \rightarrow H^+ + $$HCO_3$$^-$$

Question 17

A newborn is found to have a higher hemoglobin saturation at a given $$P_{O_2$}$$ compared to an adult. What is the physiological reason for this difference?

Accepted Answer

Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin.

Question 18

Which pressure is always lower than atmospheric pressure during normal, quiet breathing to keep the lungs inflated?

Accepted Answer

Intrapleural pressure

Question 19

Which neural centers are primarily responsible for the basic rhythm of breathing?

Accepted Answer

Medullary respiratory centers (dorsal and ventral respiratory groups)

Question 20

A patient with a partial airway obstruction is unable to move air efficiently through the bronchial tree. Which of the following best describes the correct path of air from the trachea to the alveoli?

Accepted Answer

Trachea → primary bronchi → secondary bronchi → tertiary bronchi → bronchioles → terminal bronchioles → respiratory bronchioles → alveolar ducts → alveoli

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