Which of the following is a compensatory mechanism for metabolic acidosis?

Correct Answer: D

Rationale: The correct answer is D: Increased bicarbonate production. In metabolic acidosis, the body tries to compensate by increasing the production of bicarbonate to neutralize the excess acid. This helps to restore the acid-base balance. Option A is incorrect as increased renal excretion of bicarbonate would worsen metabolic acidosis. Option B, decreased respiratory rate, would not help to compensate for metabolic acidosis as it does not directly address the excess acid. Option C, hyperventilation, is a compensatory mechanism for respiratory acidosis, not metabolic acidosis.

Correct Answer: A

Rationale: The correct diagnosis is A: Respiratory alkalosis. In this case, the patient has a high pH (alkalosis) and low PaCO₂ (hypocapnia), indicating respiratory alkalosis. Rapid breathing leads to excessive CO₂ elimination, causing a decrease in PaCO₂ and subsequent alkalosis. Choice B (Respiratory acidosis) is incorrect as the PaCO₂ is low, not high. Choice C (Metabolic alkalosis) is incorrect as the primary disturbance is respiratory, not metabolic. Choice D (Metabolic acidosis) is incorrect as the pH is elevated, not decreased.

Correct Answer: B

Rationale: The correct answer is B: Loss of bicarbonate. Severe diarrhea leads to loss of bicarbonate-rich fluids, causing metabolic acidosis. Bicarbonate is a major buffer in the body, helping to maintain pH balance. Loss of potassium (A) is more likely to cause metabolic alkalosis. Retention of hydrogen ions (C) would cause metabolic acidosis but is not the primary issue in this scenario. Retention of bicarbonate (D) would actually help correct the acidosis, not cause it.

Correct Answer: B

Rationale: The correct answer is B: Hypercalcemia. In hyperparathyroidism, there is excess parathyroid hormone leading to increased calcium levels in the blood. This results in symptoms like lethargy and bone pain. Hypocalcemia (A) is incorrect as it is the opposite of what occurs in hyperparathyroidism. Hyperkalemia (C) and Hyponatremia (D) are less likely as they are not typically associated with hyperparathyroidism. Hypercalcemia is the most common electrolyte imbalance seen in hyperparathyroidism due to increased bone resorption and calcium release.

Correct Answer: B

Rationale: The correct answer is B: Antidiuretic hormone in the posterior pituitary. When the body detects dehydration due to vomiting and diarrhea, it releases antidiuretic hormone (ADH) to promote water reabsorption in the kidneys, leading to concentrated urine. Osmoreceptors in the hypothalamus detect changes in blood osmolality, not directly related to compensatory reabsorption of water in this scenario. Baroreceptors in the carotid sinus monitor blood pressure changes, not directly involved in compensatory reabsorption of water. Insulin from the pancreas controls blood glucose levels and is not related to water reabsorption in response to dehydration.