Question

Follicle-stimulating hormone (FSH) a. is secreted by females but not by males. b. stimulates the seminiferous tubules to produce sperm. c. secretion is controlled by gonadotropin-releasing hormone (GnRH) d. Both b and c are correct.

Short answer

d. Both b and c are correct.

Step-by-step solution

Statement a: FSH is secreted by females but not by males

This statement is incorrect. FSH is secreted by the pituitary gland in both males and females. In females, FSH plays a role in the development of ovarian follicles, while in males, FSH is involved in sperm production.

Statement b: FSH stimulates the seminiferous tubules to produce sperm

This statement is correct. In males, FSH is responsible for stimulating the seminiferous tubules, which are the structures in the testes where sperm are produced.

Statement c: FSH secretion is controlled by gonadotropin-releasing hormone (GnRH)

This statement is also correct. GnRH is released by the hypothalamus and signals the pituitary gland to secrete FSH, as well as luteinizing hormone (LH).

Statement d: Both b and c are correct

Since statements b and c are both correct, statement d is also the correct choice. So the correct answer is: d. Both b and c are correct.

Key concepts

FSH in the reproductive system

Follicle-stimulating hormone (FSH) plays a critical role in the functioning of the reproductive system for both males and females.

In males, FSH is vital for testicular function and, as highlighted in the exercise solutions, is directly responsible for the stimulation of the seminiferous tubules within the testes. The seminiferous tubules are where spermatogenesis—the production of sperm—occurs. FSH works in concert with testosterone to regulate sperm production, ensuring that fertile sperm are continuously produced throughout a man's life after puberty.

In females, FSH contributes to the menstrual cycle by prompting the growth of ovarian follicles, each containing an egg. As the ovarian follicles mature, they produce estrogen, helping to prepare the uterus for potential pregnancy. Ensuring an understanding of FSH's role in these processes is essential for grasping how the endocrine system influences fertility.

Gonadotropin-releasing hormone (GnRH)

Gonadotropin-releasing hormone (GnRH) is a hormone that originates in the hypothalamus, a crucial area in the brain responsible for many hormonal regulations. GnRH acts as a master switch that commands the pituitary gland to release gonadotropins—FSH and luteinizing hormone (LH)—into the bloodstream.

By realizing the importance of GnRH, students can see the hierarchical structure of hormonal control. Precisely, GnRH stimulates the secretion of FSH in a pulsatile manner, which means that it's released in bursts rather than being continuously secreted. This pulsatile release is significant for proper reproductive function as it helps to synchronize the body's reproductive processes with the cycles of hormone production. By understanding this pulsatile nature of GnRH secretion, students can better grasp the complexities of hormonal regulation within the reproductive system.

Sperm production

Sperm production, or spermatogenesis, is a sophisticated process that takes place within the male reproductive system, specifically in the seminiferous tubules of the testes. FSH, together with testosterone produced by the testes, governs this process. Sperm production starts at puberty and generally continues without interruption throughout a man's life.

Understanding the intricate stages of spermatogenesis, from the development of spermatogonia to the final formation of mature spermatozoa, is essential for comprehending male fertility. It is a tightly regulated process that takes about 64 days to complete and encompasses several phases, including mitosis, meiosis, and spermiogenesis. This continuous cycle of sperm production means that viable sperm are always available for ejaculation, increasing the opportunity for fertilization when mating.