Q: Which equation correctly represents the reaction catalyzed by carbonic anhydrase in red blood cells?

$$\mathrm{CO_2$} + \mathrm{H_2O} \xrightarrow{\text{carbonic anhydrase}} \mathrm{H_2CO_3} \rightarrow \mathrm{H^+} + \mathrm{$$HCO_3$$^-}$$

Question 1

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

Accepted Answer

The exchange of O2 and CO2 between the blood and alveolar air across the blood-air barrier.

Question 2

According to Boyle’s Law, what happens to the pressure of a gas if the volume of its container is halved?

Accepted Answer

The pressure doubles. $$P = \frac{1}{V}$$

Question 3

During inhalation, which muscles are primarily responsible for increasing the volume of the thoracic cavity?

Accepted Answer

Diaphragm and external intercostal muscles

Question 4

A patient with emphysema has increased lung compliance. Which of the following is a direct consequence of this change?

Accepted Answer

Air moves in and out of the lungs more easily, but oxygen absorption is restricted due to loss of alveolar surface area.

Question 5

Which equation correctly represents the reaction catalyzed by carbonic anhydrase in red blood cells?

Accepted Answer

$$\mathrm{CO_2$} + \mathrm{H_2O} \xrightarrow{	ext{carbonic anhydrase}} \mathrm{H_2CO_3} ightarrow \mathrm{H^+} + \mathrm{$$HCO_3$$^-}$$

Question 6

Which of the following best explains why gas exchange in the lungs is so efficient?

Accepted Answer

Large differences in partial pressure, short diffusion distances, lipid solubility of gases, large surface area, and coordinated blood and airflow.

Question 7

A scuba diver surfaces too quickly and experiences joint pain due to nitrogen bubbles forming in the bloodstream. Which gas law explains this phenomenon?

Accepted Answer

Henry’s Law: At a given temperature, the amount of gas in solution is proportional to its partial pressure.

Question 8

Which of the following is true regarding the oxygen-hemoglobin saturation curve?

Accepted Answer

A decrease in pH or an increase in temperature shifts the curve to the right, causing more oxygen to be released.

Question 9

Which of the following is NOT a factor that affects lung compliance?

Accepted Answer

Partial pressure of oxygen in alveolar air

Question 10

During forceful exhalation, which muscles are primarily involved?

Accepted Answer

Internal intercostal, transversus thoracis, and abdominal muscles

Question 11

A patient is diagnosed with pneumothorax. What is the immediate physiological consequence?

Accepted Answer

The lung collapses due to loss of the fluid bond between pleurae, causing elastic fibers to recoil.

Question 12

Which of the following pulmonary volumes is defined as the amount of air moved in and out of the lungs during a normal respiratory cycle?

Accepted Answer

Resting tidal volume ($$V_T)$$

Question 13

Calculate the vital capacity for a male with the following values: $$ERV = 1000\ 	ext{ml}$$, $$V_T = 500\ 	ext{ml}$$, $$IRV = 3300\ 	ext{ml}. $$Use the formula $$	ext{Vital Capacity} = ERV + V_T + IRV.$$

Accepted Answer

$$4800\ 	ext{ml}$$

Question 14

Which of the following statements about gas solubility in plasma is correct?

Accepted Answer

CO2 is more soluble in plasma than O2 or N2.

Question 15

Which of the following best describes the effect of hypercapnia on respiration?

Accepted Answer

Increased arterial PCO2 stimulates chemoreceptors, leading to increased rate and depth of breathing.

Question 16

Which of the following is a direct effect of carbon monoxide (CO) poisoning?

Accepted Answer

CO binds to hemoglobin 200 times more strongly than O2, preventing oxygen transport.

Question 17

Which of the following is true regarding fetal hemoglobin compared to adult hemoglobin?

Accepted Answer

Fetal hemoglobin binds more O2 at the same PO2, allowing the fetus to extract oxygen from maternal blood.

Question 18

Which of the following is NOT a way CO2 is transported in the bloodstream?

Accepted Answer

Bound to surfactant molecules in alveoli

Question 19

Which neural structure is primarily responsible for setting the basic rhythm of respiration?

Accepted Answer

Respiratory rhythmicity center of the medulla oblongata

Pulmonary Ventilation and Gas Exchange: The Respiratory System

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