reproductive system Flashcards
hormone in female reproduction
Hormone control of female reproduction The CNS brain control the release of GnRH from hypothalamus, GnRH released from hypothalamus and act on anterior pituitary Drive the stimulation of LH and FSH. LH and FSH can act on ovaries. FSH stimulate gamate production, LH act to stimulate steroid and peptide hormone, also important for gamate production and maturation -ve fb loop on gonadal hormones producing by ovaries, fb on hypothalamus may stimulate or inhibit GnRH secretion and fb on pituitary to regulate FSH and LH as well.
Days 1-5: Menstrual bleeding (menstruation)
Functional layer of endometrium, including glands and capillaries, sloughed off Initiated by sudden drop in oestrogen and progesterone that occurred around day 25 in previous cycle Days 1-10: Oestrogen (and inhibin) initially inhibit anterior pituitary secretion of FSH and LH by negative feedback After day 10 very high oestrogen has a positive feedback on anterior pituitary and hypothalamus, causing a surge of LH stimulating ovulation
Days 5-14: Endometrial proliferative (Follicular) phase
Regrowth of lost endometrial tissue, glands, capillaries Occurs due to increasing levels of oestrogen from ovarian follicles
Days 14-25: Endometrial Secretory (Luteal) Phase:
Endometrium becomes glandular due to oestrogen and progesterone from corpus luteum Glands secrete nutritive juices to nourish fertilised ovum (if present) Cervical plug of mucus forms Days 14-25: High levels of oestrogen and progesterone inhibit LH and FSH secretion from anterior pituitary by negative feedback
Days 25-28: Reduced endometrial functioning, secretions decreasing
Due to decreased levels of oestrogen & progesterone as corpus luteum dies and becomes a corpus albicans
feedback mechanism
blue is inhibition, red is stimulatory
hormones in the production of sperm
–Takes place in seminiferous tubules of testes
– Begins at puberty & continues for life
– 70-150 million sperm produced per day
–Process takes about 70-80 days
–Complete maturation of sperm takes place in the epididymides –Sperm fully mature in female reproductive tract
feedback in male hormones
what does testosterone do in male
–anabolic steroid, derived from cholesterol
–synthesised in interstitial cells (Leydig cells) of testes
–completes spermatogenesis (FSH initiates spermatogenesis)
–stimulates formation & maintenance of male reproductive organs
–promotes secondary sex characteristics (bigger bones & muscles, deep voice, body hair)
–responsible for libido & aggression
–maximum levels in early adulthood, diminishes to 20% of peak by age 80
Hormonal feedback mechanisms - male
–Inhibin (secreted when sperm count is high) inhibits anterior pituitary secretion of FSH (and possibly hypothalamic secretion of GnRH)
–High testosterone inhibits hypothalamic secretion of GnRH
