Night blindness (Hemeralopia, Nyctalopia) is

Correct Answer: C

Rationale: The correct answer is C because night blindness (Hemeralopia, Nyctalopia) is a condition where vision is normal in daylight but weak or lost in dim light due to vitamin A deficiency. Vitamin A is essential for the conversion of light into electrical signals in the retina, crucial for night vision. Choice A refers to extreme dryness of the conjunctiva, not night blindness. Choice B describes xerophthalmia, a condition associated with severe vitamin A deficiency leading to corneal issues, not night blindness. Therefore, the correct answer is C as it accurately defines night blindness due to vitamin A deficiency.

Correct Answer: A

Rationale: Step 1: Parathyroid hormone (PTH) increases serum calcium levels by stimulating bone resorption and kidney reabsorption of calcium. Step 2: PTH decreases serum phosphate levels by promoting renal excretion of phosphate. Step 3: Therefore, the statement that PTH increases serum calcium and decreases serum phosphate is true. Step 4: Choice A is correct as it accurately reflects the actions of PTH. Step 5: Choices B, C, and D are incorrect as they do not accurately reflect the effects of PTH on serum calcium and phosphate levels.

Correct Answer: D

Rationale: The correct answer is D because calcium interactions with other drugs involve various mechanisms. Ethanol decreases calcium absorption, loop diuretics increase renal excretion of calcium, and glucocorticoids stimulate renal excretion. Therefore, all of the above options are correct in describing different interactions of calcium with these drugs. The incorrect choices are A, B, and C because they do not accurately represent the interactions with calcium as described in the question.

Correct Answer: D

Rationale: The correct answer is D: Collecting duct. Spironolactone is a potassium-sparing diuretic that acts on the aldosterone receptor in the collecting duct of the nephron. This inhibits sodium reabsorption and potassium secretion, leading to increased excretion of sodium and water while retaining potassium. The other choices (A, B, C) are incorrect because spironolactone does not primarily act on the proximal convoluted tubule, ascending thick limb of the loop of Henle, or distal convoluted tubule.

Correct Answer: B

Rationale: The correct answer is B: Griseofulvin. Griseofulvin is used for dermatomycosis treatment because it is an antifungal medication specifically effective against dermatophytes. It works by disrupting the formation of fungal cell walls, leading to their destruction. Nystatin (A) is primarily used for yeast infections, not dermatomycosis. Amphotericin B (C) is a broad-spectrum antifungal, but it is not commonly used for dermatomycosis due to its potential side effects. Vancomycin (D) is an antibiotic effective against bacteria, not fungi. Therefore, the most appropriate choice for dermatomycosis treatment is Griseofulvin.