During inspiration

Correct Answer: C

Rationale: During inspiration, the diaphragm contracts, causing it to move downward and increase the thoracic space. This creates a negative pressure in the lungs, allowing air to rush in. Choice A is incorrect as the diaphragm contracts rather than relaxes during inspiration. Choice B is incorrect since other muscles like the external intercostals also aid in expanding the thoracic cavity. Choice D is incorrect because it combines a correct statement with an incorrect one. Therefore, the correct answer is C as it accurately describes the process of inspiration involving both diaphragm contraction and an increase in thoracic space.

Correct Answer: C

Rationale: The correct answer is C: Lungs. Carbonic anhydrase is an enzyme that catalyzes the interconversion of carbon dioxide and water to carbonic acid, which plays a crucial role in maintaining acid-base balance in the body. In the lungs, carbonic anhydrase helps regulate the levels of carbon dioxide and bicarbonate in the blood by facilitating the exchange of gases during respiration. This enzyme is not predominantly found in the liver, kidneys, or stomach, as their functions are not directly related to gas exchange or acid-base balance.

Correct Answer: B

Rationale: The correct answer is B because chronic stable angina is caused by insufficient blood flow due to narrowing of the coronary arteries, leading to inadequate oxygen supply to the heart muscle during exertion. This results in chest pain. A is incorrect as there is no rubbing of epicardium against the pericardial sac in chronic stable angina. C is incorrect as the pain is not due to irritation of cardiac nerve endings in the chest wall. D is incorrect as dilation of the coronary arteries does not cause pain in chronic stable angina; it is actually a compensatory mechanism to increase blood flow in response to decreased oxygen supply.

Correct Answer: A

Rationale: The correct answer is A: Metabolic alkalosis. Low suction can lead to excessive loss of gastric acid, causing metabolic alkalosis due to an increase in bicarbonate levels. This is because the body compensates for the loss of acid by retaining bicarbonate. Choices B, C, and D are incorrect because low suction does not directly affect metabolic acidosis, respiratory alkalosis, or respiratory acidosis.

Correct Answer: B

Rationale: The blood gas values indicate respiratory alkalosis due to a high pH (7.52) and low pCO2 (20 mmHg). The normal pO2 and low bicarb suggest partial renal compensation. The kidneys retain HCO3- to partially offset the respiratory alkalosis. Metabolic alkalosis (A) is incorrect as bicarb is low. Metabolic acidosis (C) is incorrect due to the high pH. Respiratory acidosis (D) is incorrect as pCO2 is low. In summary, the correct answer is B as it aligns with the blood gas values and the concept of compensation.