Concerning the islets of Langerhan

Correct Answer: D

Rationale: Insulin release from β-cells involves glucose metabolism, depolarizing the membrane, opening Ca²⁺ channels for exocytosis core mechanism. β-cells are ~60-80%, not 90%. D cells secrete somatostatin, not pancreatic polypeptide (PP cells). Pork insulin, not beef, is closer to human (1 amino acid difference vs. 3). Ca²⁺-driven release distinguishes insulin secretion, critical for glucose response, unlike cell proportion, hormone, or species errors.

Correct Answer: A

Rationale: Insulin uses tyrosine kinase receptors (membrane-bound), driving glucose uptake via signaling cascades. Glucagon, PTH, and ACTH use G-protein-coupled receptors (GPCRs), activating cAMP similar mechanism. Insulin's distinct receptor type distinguishes it, key to its anabolic action, unlike cAMP-mediated hormones.

Correct Answer: A

Rationale: Growth hormone (GH) from the anterior pituitary promotes body growth by stimulating protein synthesis and cell division, unlike prolactin (milk production) or thyrotropin (thyroid stimulation). Though options are cut off, 'A' aligns with GH's role. This distinguishes GH's systemic anabolic effects, essential for development, contrasting with lactation or metabolic regulators.

Correct Answer: A

Rationale: Antidiuretic hormone (ADH) secretion from the posterior pituitary increases with high blood osmotic pressure, signaling dehydration, prompting water reabsorption in kidneys. Blood calcium, oxygen, or glucose levels don't directly regulate ADH calcium affects PTH, oxygen respiration, glucose insulin/glucagon. 'All choices' is incorrect as ADH's osmoregulatory role is specific. This distinguishes ADH's function in fluid homeostasis, critical for preventing dehydration, contrasting with unrelated metabolic or respiratory triggers.

Correct Answer: D

Rationale: Long-term stress boosts lipolysis, gluconeogenesis, and protein breakdown for energy, suppresses digestion not glycogenesis (glucose storage), which insulin drives. 'Digestive activities' (D) fits as incorrect. This distinguishes stress's catabolic shift, critical for resource allocation, contrasting with anabolic or digestive priorities.