Underproduction of growth hormone during the growing years produces

Correct Answer: C

Rationale: GH underproduction in childhood causes pituitary dwarfism short stature from poor bone growth pre-closure. Myxedema is adult hypothyroidism low metabolism. Gigantism is GH excess tallness. Acromegaly is adult excess thickening. Dwarfism's growth deficit distinguishes it, key to GH's developmental role, unlike thyroid or excess conditions.

Correct Answer: B

Rationale: ANH, from right atrial cells, responds to stretch (high volume), lowering pressure via natriuresis cardiac origin. Kidney tubules respond, not produce. Adrenal cortex makes aldosterone, opposing ANH. Pancreas focuses on glucose. Atrial production distinguishes ANH, key to heart-volume regulation, unlike renal, adrenal, or metabolic sources.

Correct Answer: D

Rationale: Progesterone (ovaries) grows the uterus, preparing it for pregnancy endometrial thickening. Secondary sex characteristics (e.g., breasts) are estrogen-driven, not progesterone. Estrogen aids follicle growth, not ovum maturation directly LH triggers that. Estrogen does aid breast development false to deny. Uterine growth distinguishes progesterone, key to reproductive support, unlike characteristics, maturation, or breast errors.

Correct Answer: B

Rationale: Synaptic signaling occurs when neurons release neurotransmitters (e.g., acetylcholine) across synapses to influence adjacent neurons fast, local neural communication. Autocrine involves cells signaling themselves (e.g., growth factors). Paracrine affects nearby cells (e.g., histamine), not specifically neurons. Endocrine uses blood for distant targets (e.g., insulin), not neuron-neighbor. Synaptic specificity distinguishes it, key to nervous system function, unlike self, nearby, or systemic signaling.

Correct Answer: B

Rationale: Adrenal medulla secretes adrenaline and noradrenaline (epinephrine/norepinephrine) catecholamines for fight-or-flight. T4/T3 (thyroid) regulate metabolism, not medullary. Insulin/glucagon (pancreas) manage glucose, not adrenal. Aldosterone/cortisol (adrenal cortex) are steroids, not medulla. Adrenaline-noradrenaline's neural-endocrine role distinguishes them, critical for acute stress, unlike thyroid, pancreatic, or cortical hormones.