Pro-opiomelanocortin (POMC) is a prohormone for __________.

Correct Answer: A

Rationale: Rationale: POMC is processed into various peptide hormones, including adrenocorticotropic hormone (ACTH). ACTH is produced by the pituitary gland and stimulates the adrenal glands to release cortisol. This is why option A is correct. Growth hormone, thyroxin, and insulin are not derived from POMC, making options B, C, and D incorrect.

Correct Answer: a

Rationale: The correct answer is A because hormones and neurotransmitters do not require a synapse to communicate with other cells. Hormones are typically released into the bloodstream and travel throughout the body to target cells with specific receptors. Neurotransmitters, on the other hand, communicate across synapses between nerve cells. Choice B is correct as hormones only affect cells with specific receptors. Choice C is correct as hormones can indeed influence gene expression in target cells. Choice D is correct as G proteins and cAMP are common second messengers that help transmit the hormonal signal within the cell.

Correct Answer: B

Rationale: Step 1: Islets of Langerhans are clusters of cells in the pancreas. Step 2: These cells secrete insulin to lower blood sugar levels and glucagon to raise blood sugar levels. Step 3: Therefore, choice B is correct as it accurately describes the function of the islets of Langerhans. Summary: Choices A, C, and D are incorrect as islets of Langerhans are not found in the adenohypophysis, do not secrete steroids, and do not secrete releasing hormones.

Correct Answer: D

Rationale: The correct answer is D because the adrenal medulla is primarily involved in the production of catecholamines, specifically epinephrine and norepinephrine, which are associated with the fight-or-flight response. This response is triggered by stress and prepares the body for action by increasing heart rate, dilating airways, and redirecting blood flow. On the other hand, the regulation of sugar, salt, and sex hormones is mainly controlled by the adrenal cortex, not the adrenal medulla. Therefore, while choices A, B, and C are directly related to the adrenal medulla's function, choice D is least associated with it.

Correct Answer: B

Rationale: The correct answer is B: hyperglycemia. Insulin deficiency leads to an inability to regulate blood sugar levels, resulting in elevated blood glucose levels. Without insulin, glucose cannot enter cells for energy utilization, leading to hyperglycemia. The other choices are incorrect because: A: Hypocalcemia is low calcium levels, not caused by insulin deficiency. C: Cushing syndrome is a hormonal disorder caused by prolonged exposure to high levels of cortisol, not related to insulin deficiency. D: Adrenal shock is a life-threatening condition due to insufficient adrenal gland function, not directly caused by insulin deficiency.