Which of the following statements about the hormone glucagon is true?

Correct Answer: C

Rationale: The correct answer is C: Glucagon promotes the breakdown of glycogen in the liver. Glucagon is secreted by the alpha cells in the islets of Langerhans in response to low blood glucose levels. When released, glucagon stimulates the liver to break down glycogen into glucose through a process called glycogenolysis, thus increasing blood glucose levels. This helps maintain blood glucose homeostasis during fasting or low glucose conditions. Options A and B are incorrect because glucagon is secreted by alpha cells, not beta cells, and in response to low blood glucose, not high. Option D is incorrect as glucagon promotes glycogen breakdown, not synthesis.

Correct Answer: C

Rationale: Step-by-step rationale: 1. Hyperthyroidism is an overactive thyroid gland. 2. Heat intolerance is a common symptom due to increased metabolic rate. 3. Weight gain is associated with hypothyroidism, not hyperthyroidism. 4. Dry skin is more commonly seen in hypothyroidism. 5. Bradycardia (slow heart rate) is not typical in hyperthyroidism. Summary: Choice C, heat intolerance, is associated with hyperthyroidism due to increased metabolic activity. Choices A, B, and D are incorrect as they are more commonly associated with hypothyroidism or other conditions.

Correct Answer: D

Rationale: The correct answer is D: Acromegaly. Excessive growth hormone in adults leads to acromegaly, characterized by enlargement of bones and tissues. This occurs because the growth plates have already closed in adults, preventing the elongation of bones seen in gigantism (choice A). Tetany (choice B) is caused by low calcium levels, not growth hormone. Kidney failure (choice C) is not directly related to excessive growth hormone.

Correct Answer: D

Rationale: The correct answer is D: low levels of calcium in the blood. Parathyroid hormone is released in response to low blood calcium levels to help increase calcium levels by promoting its release from bones and enhancing its absorption in the intestines. This response helps maintain calcium homeostasis. TSH from the posterior pituitary gland (choice A) is not related to parathyroid hormone release. High levels of calcium in the blood (choice B) would not stimulate parathyroid hormone release as it is released in response to low calcium levels. Calcitonin from the anterior pituitary gland (choice C) actually works in opposition to parathyroid hormone by promoting calcium deposition in bones and decreasing blood calcium levels.

Correct Answer: D

Rationale: The correct answer is D because glucocorticoids inhibit the inflammatory response by suppressing the immune system. Glucocorticoids reduce inflammation by blocking the production of inflammatory substances like prostaglandins and cytokines. This effect is only observed in large amounts of glucocorticoids. Choices A, B, and C are not produced exclusively by large amounts of glucocorticoids. Normal responsiveness of fat depots to norepinephrine and maintenance of normal vascular reactivity are not directly related to glucocorticoids in large amounts. Increased excretion of a water load is more influenced by other factors such as hydration status and renal function.