Which of the following increases Ca2+ absorption?

Correct Answer: D

Rationale: A high protein diet increases Ca2+ absorption by enhancing intestinal acidity and amino acid-mediated uptake. Oxalates and phosphates bind Ca2+, reducing absorption; alkalis and high Ca2+ intake have less direct effect.

Correct Answer: C

Rationale: Lysine is an essential amino acid that must be obtained from the diet, unlike glycine, serine, glutamine, and tyrosine, which can be synthesized.

Correct Answer: C

Rationale: MMC occurs during fasting to clear the gut, distinct from BER; secretions decrease, and Phase I is quiescent, not contractile.

Correct Answer: C

Rationale: Gastrin stimulates histamine release from ECL cells, increasing acid secretion; histamine acts via cAMP, not Ca2+.

Correct Answer: D

Rationale: The adrenal medulla secretes epinephrine and norepinephrine.