Which hormone is responsible for the development of male secondary sexual characteristics?

Correct Answer: A

Rationale: The correct answer is A: Androgens. Androgens, such as testosterone, are responsible for the development of male secondary sexual characteristics, such as facial hair, deep voice, and muscle growth. Follicle-stimulating hormone (B) is involved in sperm production, not male secondary sexual characteristics. Epinephrine (C) and norepinephrine (D) are stress hormones and not related to the development of male secondary sexual characteristics.

Correct Answer: B

Rationale: The correct answer is B: Secondary hyperaldosteronism. In this scenario, the low renin-angiotensin levels indicate a feedback mechanism where the body is trying to compensate for high aldosterone levels. Secondary hyperaldosteronism, which can be caused by conditions like renal artery stenosis or heart failure, leads to increased aldosterone secretion independent of renin levels, resulting in low renin-angiotensin levels. A: Cushing's syndrome is associated with excess cortisol production, but it does not directly influence renin-angiotensin levels. C: Primary hyperaldosteronism (Conn's syndrome) is characterized by high aldosterone levels, not low renin-angiotensin levels. D: Both Cushing's syndrome and secondary hyperaldosteronism do not necessarily occur together, making this option incorrect.

Correct Answer: A

Rationale: The correct answer is A: a capillary network. The hypothalamus secretes hormones into the capillary network called the hypothalamic-hypophyseal portal system. These hormones travel directly to the anterior pituitary gland to regulate the release of its own hormones. Choice B is incorrect because neurons do not directly connect the hypothalamus and pituitary gland. Choice C is incorrect because Schwann cells are involved in myelination of peripheral nerves, not hormone transport. Choice D is incorrect because although both options A and B involve communication between the hypothalamus and pituitary gland, it is specifically the capillary network that carries hormone messages in this case.

Correct Answer: B

Rationale: The correct answer is B: cellular mutations occur. Hormone binding typically triggers signaling cascades that lead to cellular responses like changing plasma membrane permeability, activating/inactivating enzymes, or stimulating mitosis. Cellular mutations are not a direct result of hormone binding and are typically caused by external factors like radiation or chemicals. In this context, mutations do not happen as an immediate response to hormone binding. Therefore, option B is the correct choice. Plasma membrane permeability changes, enzyme activation/inactivation, and mitosis stimulation are all typical outcomes of hormone binding and subsequent signaling pathways.

Correct Answer: A

Rationale: The correct answer is A: nervous system. The endocrine system regulates processes through hormones, while the nervous system controls body functions through electrical impulses. Both systems work together to maintain homeostasis. The other choices are incorrect because the immune system focuses on defense against pathogens, the circulatory system transports nutrients and oxygen, and the respiratory system facilitates gas exchange. Only the nervous system aligns with regulating body functions alongside the endocrine system.