Most endocrine secretions are controlled by

Correct Answer: B

Rationale: Negative feedback controls most endocrine secretions (e.g., high cortisol suppresses ACTH), maintaining homeostasis excess inhibits production. Positive feedback (e.g., oxytocin in labor) is rare, amplifying. Neural feedback is specific (e.g., medulla), not broad. Hormonal is a type, not the system. Negative feedback distinguishes endocrine stability, key to regulation, unlike amplifying or partial mechanisms.

Correct Answer: C

Rationale: GH overproduction in adults causes acromegaly bone thickening (e.g., hands, face) post-epiphyseal closure. Dwarfism is childhood GH lack. Gigantism is pre-closure excess height surge. Myxedema is hypothyroidism, unrelated. Acromegaly's adult-specific bone changes distinguish it, key to GH excess timing, unlike childhood or thyroid conditions.

Correct Answer: D

Rationale: PTH (parathyroid) raises blood calcium by bone resorption, opposing calcitonin's lowering via deposition antagonistic pair. Thyroxine (thyroid) boosts metabolism, not calcium directly. GH (pituitary) grows bones, not regulating calcium. Insulin (pancreas) lowers glucose, unrelated. PTH's calcium-raising role distinguishes it, key to homeostasis, unlike metabolic, growth, or glucose hormones.

Correct Answer: A

Rationale: ANH (atria) opposes aldosterone by promoting natriuresis, lowering blood volume/pressure antagonistic to aldosterone's sodium retention. ADH (pituitary) retains water, synergistic at times. Cortisol (adrenal) is glucocorticoid, minimal overlap. Glucagon (pancreas) raises glucose, unrelated. ANH's natriuretic effect distinguishes it, key to volume counterbalance, unlike water, stress, or glucose hormones.

Correct Answer: D

Rationale: Type I diabetes (IDDM) requires insulin injections autoimmune β-cell loss halts production. Obesity correlates with type II, not I. Type II is more common insulin resistance. Resistance defines type II, not I cells respond, lack insulin. Injection need distinguishes type I, key to its management, unlike obesity, prevalence, or resistance traits.