The largest endocrine gland is the:

Correct Answer: A

Rationale: The thyroid, in the neck, is the largest purely endocrine gland by mass, secreting thyroxine and calcitonin for metabolism and calcium regulation. Pituitary, small but master, controls others. Adrenals produce steroids and catecholamines, smaller than thyroid. Pancreas, larger, is dual endocrine (islets) and exocrine (digestion), diluting its endocrine claim. Thyroid's size and exclusive endocrine role distinguish it, vital for systemic metabolism.

Correct Answer: D

Rationale: Post-subtotal thyroidectomy, removing most thyroid tissue, the nurse monitors hypothyroidism (low T₃/T₄) and the nearby parathyroid glands, embedded in the thyroid, which regulate calcium via parathyroid hormone (PTH). Surgical disruption risks hypoparathyroidism, causing hypocalcemia (e.g., tetany). Pituitary oversees TSH but isn't local or directly affected here. Pancreas (insulin) and adrenals (cortisol) are distant, unrelated to thyroid proximity. Parathyroids' anatomical closeness and calcium role distinguish them, critical for post-surgical care, unlike systemic or distant glands.

Correct Answer: C

Rationale: Endocrine glands produce hormones chemical messengers like insulin or cortisol that enter the bloodstream, targeting distant organs to regulate processes like metabolism. Unlike exocrine glands (e.g., sweat, sebaceous) using ducts, or neurons releasing neurotransmitters into synapses, endocrine glands' blood-mediated delivery defines them. Sebaceous and sweat glands are exocrine, not endocrine. This circulatory transport distinguishes endocrine function, critical for systemic coordination, contrasting with localized synaptic or ductal mechanisms.

Correct Answer: D

Rationale: The thyroid, anterior to the trachea and below the larynx, contains embedded parathyroids (posteriorly) and produces three hormones: thyroxine (T4), triiodothyronine (T3), and calcitonin. All statements hold: location aids surgical identification, parathyroids regulate calcium, and hormones manage metabolism/calcium. This comprehensive accuracy distinguishes thyroid anatomy/function, key to endocrine physiology.

Correct Answer: D

Rationale: Fight-or-flight, driven by adrenal medulla catecholamines, includes pupil dilation (vision), increased lung oxygen (energy), and suppressed digestion (blood diversion). Mental activity heightens for alertness, not reduces. Reduced cognition contradicts this survival mechanism, distinguishing it from physiological shifts, key to acute stress response understanding.