The client's serum laboratory values indicate an elevated level of adrenocorticotropic hormone (ACTH). The nurse knows that the expected response to this increase in ACTH is the release of:

Correct Answer: A

Rationale: Elevated ACTH from the anterior pituitary stimulates the adrenal cortex's zona fasciculata to release glucocorticoids (e.g., cortisol), regulating stress and metabolism. Mineralocorticoids (e.g., aldosterone) from zona glomerulosa respond to renin-angiotensin, not ACTH primarily. Epinephrine, from the adrenal medulla, isn't ACTH-driven sympathetic signals control it. Insulin, pancreatic, counters glucose, unrelated to ACTH. Glucocorticoids' ACTH dependency distinguishes them, key to the hypothalamic-pituitary-adrenal axis, unlike electrolyte, medullary, or glucose responses.

Correct Answer: B

Rationale: Thyroid-stimulating hormone (TSH) from the anterior pituitary stimulates thyroid hormone (T3/T4) release, regulated by hypothalamic TRH. TSH isn't hypothalamic, thyroxine isn't pituitary-made, and thyroglobulin is a thyroid storage protein, not a controller. TSH's pituitary origin distinguishes it, central to the hypothalamic-pituitary-thyroid axis, critical for metabolic regulation.

Correct Answer: B

Rationale: Pinealocytes in the pineal gland secrete melatonin to regulate sleep-wake cycles, influenced by light. Melanocytes produce pigment, suprachiasmatic nucleus cells regulate circadian rhythms but don't secrete melatonin, and retinal cells detect light. Pinealocytes' secretory role distinguishes them, vital for circadian control, contrasting with pigment or regulatory cells.

Correct Answer: C

Rationale: Erythropoietin (EPO), from kidneys, stimulates red blood cell production, increasing oxygen-carrying capacity enhancing endurance. It doesn't affect calcium, growth hormone, or muscle mass directly (testosterone does). Oxygen boost distinguishes EPO's use, key to athletic performance, contrasting with skeletal or hormonal growth effects.

Correct Answer: C

Rationale: Gonads (ovaries, testes) produce steroid hormones testosterone, estrogen, progesterone from cholesterol, acting on nuclear receptors for sex traits and reproduction. Amine hormones (e.g., thyroxine) derive from tyrosine/tryptophan, from thyroid. Peptide hormones (e.g., insulin) are protein-based, from pancreas. Catecholamines (e.g., epinephrine) are adrenal medullary, not gonadal. Steroids' lipid-soluble, genomic action distinguishes them, critical for gonadal endocrine function, unlike amino-acid or peptide classes.