The primary function of T3 and T4 is to:

Correct Answer: D

Rationale: T3 (triiodothyronine) and T4 (thyroxine) from the thyroid increase metabolic rate, stimulating cellular energy use body-wide, boosting oxygen consumption and heat production. Glucose reduction is insulin's role, not thyroid hormones'. Calcitonin, also thyroid-derived from C-cells, lowers blood calcium, unrelated to T3/T4's metabolic focus. Bone growth depends on growth hormone (GH) from the pituitary, not thyroid though T3/T4 support growth indirectly via metabolism. Their metabolic acceleration distinguishes them, essential for energy regulation, unlike glucose, calcium, or growth-specific functions.

Correct Answer: D

Rationale: Adenomas, benign tumors, cause acromegaly via pituitary GH oversecretion, not hyperthyroidism (often Graves' or thyroid adenoma), hypothyroidism (deficiency), or adrenal tumors (pheochromocytoma). The answer 'hyperthyroidism' seems erroneous; acromegaly fits adenoma etiology. This pituitary link distinguishes it, key to tumor-related endocrinopathies, contrasting with thyroid or adrenal origins.

Correct Answer: C

Rationale: Salivary glands are exocrine, secreting saliva via ducts for digestion, not hormones into blood. Pancreas (insulin), testes (testosterone), and parathyroid (PTH) are endocrine, releasing hormones systemically for glucose, reproduction, and calcium regulation. Salivary's ducted, non-hormonal output distinguishes it, contrasting with endocrine glands' blood-mediated roles, key to gland classification.

Correct Answer: C

Rationale: Gonadocorticoids (androgens like DHEA) from the adrenal cortex's zona reticularis supplement gonadal sex hormones (testosterone, estrogen), contributing to puberty and libido. Mineralocorticoids (aldosterone) regulate electrolytes, glucocorticoids (cortisol) manage stress/glucose, and epinephrine/norepinephrine handle acute stress none are sex hormones. Androgens' supportive role distinguishes them, key to adrenal-gonadal synergy, unlike electrolyte or stress hormones.

Correct Answer: B

Rationale: Androgens, like testosterone, are primarily produced by the testes in males, driving male traits and spermatogenesis. Ovaries produce minor androgens, the hypothalamus regulates via GnRH, and islets secrete insulin/glucagon not androgens. Testicular production distinguishes androgen's source, key to reproductive endocrinology, contrasting with regulatory or metabolic glands.