In Which of the Following Pairs, the Hormone of Endocrine Glands and Its Primary Action Is Incorrect or Mismatched?

Correct Answer: D

Rationale: The correct answer is D - Melatonin - Regulates the rate of cellular metabolism. Melatonin is a hormone primarily involved in regulating sleep-wake cycles, not cellular metabolism. A: Calcitonin - Lower blood calcium levels - Correct. Calcitonin is released by the thyroid gland to lower blood calcium levels. B: Parathyroid - Raises blood calcium levels - Correct. Parathyroid hormone is released by the parathyroid glands to raise blood calcium levels. C: Somatostatin - Inhibits release of glucagon - Correct. Somatostatin inhibits the release of glucagon and insulin.

Correct Answer: B

Rationale: The correct answer is B: vagus. The efferent swallow reflex involves motor nerves responsible for swallowing. The vagus nerve is primarily responsible for the afferent (sensory) pathway in the swallow reflex, while the efferent pathway involves the trigeminal, facial, and hypoglossal nerves. The trigeminal nerve (A) controls chewing muscles, the facial nerve (C) is responsible for facial expressions and some swallowing muscles, and the hypoglossal nerve (D) controls the movement of the tongue during swallowing. Therefore, the vagus nerve is not directly involved in the efferent motor control of swallowing, making it the correct answer.

Correct Answer: A

Rationale: The correct answer is A because gastrin primarily stimulates gastric acid secretion and gastric mucosal growth but not insulin secretion. Gastrin acts on parietal cells to stimulate acid production and chief cells to release pepsinogen. Choice B and C are incorrect as gastrin does have a trophic effect on colonic and gastric mucosa, respectively. Choice D is also incorrect as gastrin stimulates pepsin secretion.

Correct Answer: D

Rationale: The correct answer is D because creatinine excretion is not depressed in starvation. Creatinine is a byproduct of muscle metabolism and is relatively constant even during starvation when muscle breakdown occurs. A: Incorrect, as increasing respiratory quotient > 1.0 indicates excessive carbohydrate utilization. B: Incorrect, SDA is the energy used for digestion and absorption of nutrients, not specific to protein metabolism. C: Incorrect, glucagon stimulates protein breakdown to release amino acids for energy during fasting.

Correct Answer: D

Rationale: Step 1: Activation of protein kinase A leads to phosphorylation of phosphorylase kinase. Step 2: Phosphorylase kinase phosphorylates and activates phosphorylase. Step 3: Active phosphorylase cleaves 1,4-glycosidic linkages in glycogen, not 1,6 linkages (eliminates A). Step 4: Phosphorylase is activated by phosphorylase kinase, not norepinephrine (eliminates B and C). Step 5: Inhibition of glycogen synthesis occurs when phosphorylase is activated, supporting choice D as the correct answer.