The gonads produce what class of hormones?

Correct Answer: C

Rationale: Gonads (ovaries, testes) produce steroid hormones estrogens, progesterone, testosterone from cholesterol, acting intracellularly to regulate reproduction. Amine hormones (e.g., thyroid) derive from tyrosine, peptides (e.g., insulin) from amino acids, and catecholamines (e.g., epinephrine) from adrenal medulla. Steroid's lipid-based nature distinguishes gonadal output, critical for sexual development, contrasting with other chemical classes.

Correct Answer: D

Rationale: Directing blood flow is a circulatory system function, adjusting tissue perfusion via vessels to maintain homeostasis, not an endocrine role. The endocrine system regulates immunity (e.g., cortisol affects immune cells), reproduction (e.g., FSH, LH drive gonadal function), and heart rate/blood pressure (e.g., epinephrine increases both), using hormones like adrenaline or aldosterone. Water balance, another endocrine task (e.g., ADH), was replaced here to fit four options, but blood flow direction relies on vascular dynamics, not glandular secretion. This distinction highlights endocrine's chemical signaling versus circulatory mechanics, key to system roles.

Correct Answer: B

Rationale: Hyperparathyroidism involves excess parathyroid hormone (PTH), raising serum calcium by mobilizing it from bones and increasing kidney reabsorption, while lowering phosphorus both are abnormal. Sodium, chloride, and potassium aren't directly PTH-regulated; aldosterone or ADH affect them. The question's 'select all' (calcium, phosphorus) is adapted here to single-answer (calcium), as it's the hallmark. Calcium's elevation distinguishes hyperparathyroidism, key to its pathology (e.g., kidney stones), unlike unaffected electrolytes.

Correct Answer: B

Rationale: Diabetes insipidus results from ADH deficiency or renal resistance, impairing water reabsorption, causing dilute urine and thirst. Excess GH is gigantism, other options are absent. Renal ADH unresponsiveness distinguishes it, critical for fluid balance disorders, contrasting with growth or pituitary excess conditions.

Correct Answer: C

Rationale: Hypothalamic releasing (e.g., TRH) and inhibiting (e.g., dopamine) hormones target the anterior pituitary, stimulating (e.g., TSH) or suppressing (e.g., prolactin) its hormone release to regulate endocrine glands. Liver/adipose respond to hormones (e.g., insulin), not hypothalamic signals directly. Gonads are pituitary targets (e.g., FSH), not hypothalamus'. Bone marrow isn't endocrine-regulated. Anterior pituitary's role as intermediary distinguishes it, key to the hypothalamic-pituitary axis, unlike downstream or unrelated tissues.