The endocrine gland that secretes glucagon is

Correct Answer: C

Rationale: Glucagon, which raises blood glucose by promoting glycogenolysis, is secreted by the pancreas' alpha cells. 'Pancreas,' is correct, per physiology texts like Vander's Human Physiology. 'Adrenal gland,' secretes catecholamines and cortisol, not glucagon. 'Thyroid gland,' produces T3/T4 for metabolism. 'Pituitary gland,' regulates other glands, not glucose directly. The pancreas' endocrine role in glucose homeostasis, via glucagon, distinguishes C as the accurate answer, specific to its islet cells.

Correct Answer: B

Rationale: Antidiuretic hormone (ADH) increases water reabsorption in the kidney's collecting ducts, concentrating urine. 'Antidiuretic hormone,' is correct, per physiology texts like Costanzo, acting via aquaporins. 'Aldosterone,' reabsorbs sodium, indirectly affecting water. 'Atrial natriuretic peptide,' promotes water loss. 'Adrenaline,' affects circulation, not reabsorption. ADH's direct water retention role makes B the precise answer.

Correct Answer: C

Rationale: The respiratory center, controlling breathing, is in the medulla oblongata. 'Medulla oblongata,' is correct, per physiology (e.g., Costanzo), with rhythm and depth regulation. 'Cerebrum,' handles cognition. 'Cerebellum,' coordinates movement. 'Hypothalamus,' regulates homeostasis, not breathing directly. The medulla's role makes C the accurate answer.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.