Serum Na is

Correct Answer: D

Rationale: Serum Na, or serum sodium, is regulated by both blood pressure (BP) and kidney perfusion, which play a crucial role in maintaining the balance of sodium in the body. Additionally, serum sodium levels are regulated by hormones such as aldosterone and ADH, which help control reabsorption and excretion. Serum Na also reflects blood osmolality, a measure of solute concentration in the blood. The option 'Not affected by K pumps' is incorrect as potassium-sodium pumps influence sodium levels, but the first three statements are true.

Correct Answer: C

Rationale: Chvostek sign is a clinical sign that involves the facial nerve (cranial nerve VII). It is demonstrated by tapping on the facial nerve, usually at the angle of the jaw. A positive Chvostek sign is indicated by the twitching of the facial muscles, particularly the muscles around the mouth and eye, often seen in hypocalcemia.

Correct Answer: C

Rationale: Correct Answer: C (Aldosterone) Rationale: Aldosterone is produced by the adrenal glands and plays a crucial role in regulating sodium reabsorption in the kidneys. It acts on the distal convoluted tubule and collecting ducts to increase sodium reabsorption and potassium excretion, thereby helping to maintain electrolyte balance. In contrast, ADH primarily regulates water reabsorption, ANP promotes sodium excretion, and cortisol is involved in stress response and metabolism, not sodium reabsorption in the kidneys. Therefore, aldosterone is the hormone primarily responsible for regulating sodium reabsorption in the kidneys.

Correct Answer: B

Rationale: Chronic diarrhea leads to excessive loss of fluids and electrolytes, particularly potassium (K+). Hypokalemia (B) is the most likely imbalance due to potassium being a major electrolyte in the body. Hyperkalemia (A) is less likely as diarrhea causes potassium depletion. Hypernatremia (C) is unlikely as sodium levels are not significantly affected by diarrhea. Hypocalcemia (D) is less common in chronic diarrhea compared to potassium loss. Therefore, the correct answer is B.

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.