Why can a single endocrine hormone produce a wider spread of responses in more of the body than a single nerve cell?

Correct Answer: B

Rationale: Hormones travel via blood, reaching multiple target cells body-wide, eliciting varied responses (e.g., cortisol in stress). Nerve cells target specific cells via synapses, limiting scope. Endocrine-nervous integration exists, but blood's distribution distinguishes hormonal spread, key to systemic effects, contrasting with neural precision.

Correct Answer: B

Rationale: The anterior pituitary produces growth hormone (somatotropin), driving body growth and metabolism. Pineal makes melatonin, hypothalamus regulates via GHRH, adrenals produce adrenaline/cortisol not GH. Pituitary's 'master gland' status and GH secretion distinguish it, critical for development, with hyposecretion stunting growth, contrasting with regulatory or stress glands.

Correct Answer: B

Rationale: Adrenal medulla secretes dopamine (minor), alongside epinephrine/norepinephrine, from chromaffin cells, aiding stress responses. Cortisol, primary glucocorticoid from zona fasciculata, isn't sole corticosterone exists, though less. Oestrogens (from zona reticularis) aren't largest molecular size varies, aldosterone similar. Cortisol has some mineralocorticoid activity (e.g., in excess like Cushing's), not negligible. Dopamine's medullary secretion distinguishes it, key to catecholamine diversity, unlike glucocorticoid exclusivity, size, or activity claims.

Correct Answer: D

Rationale: PTH increases urinary PO₄ excretion by inhibiting reabsorption, lowering serum PO₄ while raising Ca²⁺. Gastrin/glucagon/secretin don't notably inhibit calcitonin calcium does. Calcitonin's half-life is ~10 minutes, not 30. Calcitonin reduces bone resorption, not increases. PTH's phosphate effect distinguishes it, key to calcium-phosphate balance, unlike hormonal, kinetic, or resorption errors.

Correct Answer: D

Rationale: Oxytocin, from hypothalamus, is stored/released by posterior pituitary, not anterior lactation/childbirth role. ACTH (adrenal), prolactin (lactation), and β-lipoprotein (lipid metabolism, though less common term) are anterior pituitary hormones. Oxytocin's posterior origin distinguishes it, key to pituitary division, unlike anterior tropic hormones.