anim_hormonal_control_male_reproductive_function_answer_key.doc

Hormonal Control of Male Reproductive Function To complete this worksheet, select: Module: Continuity Activity: Animations Title: Hormonal Control of Male Reproductive Function Introduction 1. What organs are involved in hormonal control of male reproductive functions? The hypothalamus, anterior pituitary and the testes. Hormonal Control of Male Reproductive Functions 2. a. Describe gonadotropin releasing hormone (GnRH) production. Certain neurosecretory cells in the hypothalamus secrete gonadotropin releasing hormone, GnRH. This releasing hormone is then carried by the blood to the anterior pituitary where it binds to receptors on gondotrophic cells. b. Describe GnRH affects on the male anterior pituitary. GnRH then stimulates the gondotrophic cells of the anterior pituitary to increase the secretion of Leutinizing hormone and Follicle stimulating hormone. 3. What affect does luteinizing hormone (LH) have on the testes? Luteinizing hormone binds to the receptors of the Interstitial Cells of Leydig between the seminiferous tubules, and stimulates the secretion of testosterone. 4. a. What affect does testosterone and FSH have on the testes? Under the influence of FSH and testosterone, the Sertoli cells produce Androgen-binding protein (ABP). b. What affect is the affect of androgen-binding protein? Androgen – binding protein binds to testosterone and helps maintain high testosterone levels near the spermatogenic cells. 5. If you haven’t summarized it already, what affect does testosterone have on spermatogenesis? Testosterone stimulates the final stages of spermatogenesis. It is also converted to dihydrotestosterone (DHT). DHT may function to promote sperm cell formation. 6. How do testosterone and DHT affect male prenatal development? Testosterone and DHT both bind to the same intranuclear receptors. Together, these androgens regulate male prenatal development and the development of male sexual characteristics. These include enlargement of the male sex organs, secondary sex characteristics that begin at puberty and protein synthesis. 7. Describe inhibin secretion. From where? Why? Effect? Sertoli cells in the testes release a protein hormone called inhibin when the level of spermatogenesis needed for the male reproductive system has been attained. Inhibin acts as a negative feedback control on the anterior pituitary to regulate FSH secretion. Explain the negative feedback loop that regulates spermatogenesis at homeostatic levels. Inhibin is delivered to the anterior pituitary gondotrophic cells and acts on the gonadotrophs to reduce FSH secretion, thus decreasing the rate of spermatogenesis.