In males which hormone stimulates Sertoli cells to produce androgen binding globulin (ABG)?

Correct Answer: C

Rationale: Rationale for choice C (FSH) being correct: 1. FSH stimulates Sertoli cells in the testes. 2. Sertoli cells produce androgen binding globulin (ABG). 3. ABG binds to testosterone, regulating its availability. 4. FSH indirectly influences testosterone levels via ABG production. Summary of incorrect choices: A. LH stimulates Leydig cells to produce testosterone, not Sertoli cells. B. GnRH regulates the release of FSH and LH but does not directly stimulate ABG production. D. Oxytocin is not involved in the regulation of Sertoli cells or ABG production in males.

Correct Answer: C

Rationale: Leydig cells are found in the testes and are responsible for producing testosterone, a crucial male sex hormone. This hormone is essential for the development of male reproductive organs, secondary sexual characteristics, and sperm production. Oestrogen is primarily produced by the ovaries in females. Androgen binding globulin is a protein that binds to testosterone in the bloodstream but is not produced by Leydig cells. Semen is produced by the accessory glands in the male reproductive system, not by Leydig cells. Therefore, the correct answer is C: Testosterone.

Correct Answer: B

Rationale: The correct answer is B: ductless. Endocrine glands release hormones directly into the bloodstream without the use of ducts. This allows hormones to reach target organs throughout the body. Choice A (vascular) is incorrect because it refers to the presence of blood vessels, which is common in all glands, not just endocrine glands. Choice C (square) is irrelevant as the shape of glands does not determine their function. Choice D (autonomous) is incorrect as it does not accurately describe endocrine glands; while they function independently, the term "autonomous" does not specifically apply to them.

Correct Answer: D

Rationale: The correct answer is D: second messengers. Protein hormones typically bind to cell surface receptors, activating second messenger systems to relay the signal inside the cell. This mechanism allows for rapid and amplified cellular responses. Choices A and B (cytoplasmic and nuclear receptors) are more commonly associated with steroid hormones, not protein hormones. Choice C (cyclic ribosomal adenosine phosphate) is not a known mechanism of hormone action. Thus, the correct answer is D, as second messengers are the primary mediators of protein hormone actions.

Correct Answer: A

Rationale: The correct answer is A because ADH secretion is increased during stress to retain water in the body. This response helps maintain blood pressure and prevent dehydration under stressful conditions. Choice B is incorrect because ADH secretion is actually increased during hemorrhage to conserve water. Choice C is incorrect because increased blood osmolality triggers ADH secretion to retain water. Choice D is incorrect because alcohol inhibits ADH secretion, leading to increased urine production.