Female reproductive system.docx

Female reproductive system I. Introduction - female reproductive system far more complex than male: production of sex cells production of sex hormones receive penis during sexual intercourse create environment for implantation create environment for embryo development - sex organs: ovaries; produce...

Female reproductive system I. Introduction - female reproductive system far more complex than male: production of sex cells production of sex hormones receive penis during sexual intercourse create environment for implantation create environment for embryo development - sex organs: ovaries; produce eggs and sex hormones - accessory ducts: oviducts (uterine tubes), uterus, vagina - external sex organs: external genitalia, vulva - mammary glands II. Anatomy of female reproductive system A. Ovaries - paired, flank uterus on each side, almond-shaped - X-section: outer layer with forming gametes at different stages of development; inner layer region has blood vessels, nerves - in cortex see ovarian follicles: one or more layer(s) of cells surrounding an immature egg, oocyte. surrounding cells called follicular cells at birth woman has many follicles each containing an oocyte every month at least one follicle and associated oocyte stimulated to develop follicle matures, oocyte "released" through ovulation fertilization -- completes maturation. "leftover" follicle -- corpus luteum -- becomes endocrine gland B. Uterine tubes - receive ovulated oocyte, provide site where fertilization occurs; very muscular walls - fimbriae with cilia draw egg into tubes; peristalsis moves egg to uterus - ectopic pregnancy -- fertilization and implantation in peritoneal cavity. C. Uterus - hollow, thick walled organ: receives, retains, nourishes fertilized ovum - size/shape of inverted pear; during pregnancy up to 60X original size - layers: perimetrium: outermost, visceral peritoneum myometrium: bulky, interlacing bundles of smooth muscle endometrium: mucosal lining of uterine cavity, undergoes cyclical changes in response to blood levels of ovarian hormones D. Vagina - thin-walled tube, 8-10 cm long, extends from vestibule to cervix. receives penis/semen during intercourse provides passageway for delivery during childbirth highly distensible wall very well vascularized acidic mucosa to prevent infection E. External genitalia - collectively known as vulva. mons pubis rounded area overlying pubic symphysis. labia majora two hair-covered skin folds surrounding vaginal and urethral openings. homologous to male scrotum labia minora two hairless skin folds enclose space called vestibule. homologous to ventral penis vestibule space within labia minora that contains external openings of urethra and vagina. flanking vagina are vestibular glands that release mucous into vestibule. moisten, lubricate, facilitate intercourse. homologous to bulbourethral glands in male clitoris: anterior to vestibule erectile tissue, homologous to penis covered by thin fold, prepuce. F. Mammary glands: present in both sexes only functional in female; modified sweat glands internally divided into 15-20 lobes by CT lobes divided into lobules that contain secretory units or alveoli that empty secretion into lactiferous duct system unite at nipple III. Physiology of female reproduction A. Oogenesis - note that in male gamete production begins at puberty; in female preparation for gamete production begins in fetus. stem cells -- oogonia oogonia divide mitotically (several million) enlarge, mature -- before birth cells become primary oocytes when they begin first meiotic division (DNA replicated) division is stalled prior to birth. primary oocyte enclosed by follicular cells at puberty under appropriate stimulation follicle growth completion of first meiotic division secondary oocyte and polar body ovulation when fertilized second meiotic division takes place ovum and polar body - thus at birth all of women's potential eggs formed: of about 2 million follicles, at birth about 700,000 remain; by puberty about 300-400,000 left. B. Ovarian cycle - follicular phase: period of follicular growth, d1-d14 - luteal phase: period of corpus luteum activity, d14-d28 1. follicular phase starting at puberty a group of follicles stimulated to continue development every 28 days follicle cells divide follicle cells begin to produce estrogen. complete meiosis I ovulation meiosis II 2. luteal phase: a. remaining follicular cells begin producing progesterone, estrogen – corpus luteum (CL) b. if fertilization occurs, the embryo produces human chorionic gonadotrophin (HCG) which maintains CL until placenta can kick in its own progesterone/estrogen production. c. if fertilization does not occur, CL degenerates as no HCG. C. Hormonal regulation of ovarian cycle - feedback inhibition patterns: low level of estrogen inhibits FSH/LH high level of estrogen stimulates LH/FSH release D. Uterine cycle: menstrual cycle, regulated by ovarian hormones. d1 of cycle, est/prog very low -- shed endometrium FSH level begin to increase due to lack of feedback inhibition. FSH stimulates follicle growth follicles produce estrogen. uterine build up as estrogen levels increase, LH/FSH spike ovulation estrogen levels begin to drop. corpus luteum develops -- secretes progesterone/some estrogen. builds up endometrium and prepares it for implantation. depending on if HCG present or not, CL maintained or degenerates and likewise endometrium E. Extra-uterine estrogen effects - female secondary sex characteristics: increased deposits of subcutaneous fat, widening, lightening of pelvis; growth of axillary and pubic hair. - maturation of reproductive structures F. Female sexual response 1. excitement or arousal: sexual arousal results from: psychological stimuli physical stimuli tactile stimulation of clitoris and external genitalia stimuli trigger neural reflexes parasympathetic induced vasodilation of arterioles throughout vagina and external genitalia swelling of labia. erection of clitoris - more sensitive to stimulation increased flow through vaginal capillaries fluid forced out of vessels into vaginal lumen. lubricant for intercourse increased vestibular gland activity breast enlarge and nipples erect as result of Vaso congestion nipples very sensitive -- stimulation increases neural influences on vagina, external genitalia 2. Plateau - changes initiated during excitement phase intensify lower third of vagina swells with blood tighten around penis simultaneously uterus contracts upwards, lifts cervix, enlarges upper two thirds of vagina space for ejaculate systemic effects increased BP, respiratory rate, muscle tension 3. Orgasm - at certain level of arousal, massive, whole body neural discharge lower third of vaginal canal and uterus contract rhythmically pelvic musculature contracts rhythmically increased HR/BP endorphin/enkephalin release sexual intensity can diminish to plateau -- brought back to peak again no refractory period no ejaculate