Anatomy and Physiology Answer Key

A fsh b lh 2 a estrogen b promotes repair and growth

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Unformatted text preview: the product of a series of (hormone controlled) reactions controls its own production by turning off the pathway when it reaches a certain level. Each stage in the cycle is precisely controlled by the interplay of various hormones and the negative feedback effect that they have on their controlling factors (hormones). Exemplar: e.g. one hormone (e.g. estrogen) is produced as a result of the activity of another hormone (e.g. FSH). At a certain level, the estrogen inhibits further FSH release so that the further development of follicles is prevented. Estrogen levels then fall and the next stage in the cycle can proceed. 3. In males FSH and LH (called ICSH in males) regulate spermatogenesis (sperm production). Note that ICSH operates through stimulating testosterone secretion. Biozone International 2009 Photocopying Prohibited 35 Hormone Main site of secretion Main effects and site of action during the menstrual cycle GnRH Hypothalamus Stimulates anterior pituitary to secrete LH and FSH. FSH Anterior pituitary Stimulates the growth of ovarian follicles. LH Anterior pituitary Stimulates ovulation and development of corpus luteum. Estrogens Graafian follicle At high level, stimulates LH surge. Promotes growth and repair of uterine lining. Progesterone Corpus luteum Maintains endometrium. Inhibits FSH/LH. Sharp drop triggers menstruation. Male Reproductive System (page 215) (a) (b) (c) (d) 2. (a) Conducts sperm to the urethra. (b) Stores urine. (c) Produces secretions that add to the semen (in lower vertebrates and invertebrate the seminal vesicles may store the sperm). (d) Produces secretions that forms part of the semen. (e) Conducts sperm and urine to the outside. (f) Produces sperm and testosterone (male hormone). (g) Holds the testes (outside the body at the cooler temperature required for sperm production). 3. 4. 5. 6. Vas deferens Bladder Seminal vesicle Prostate gland (c) Fusion of the egg and sperm membranes: Enables the sperm nucleus to enter the egg. The fusion causes a sudden depolariza...
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