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53 Cards in this Set
- Front
- Back
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What are the exceptions to homeostatic mechanisms?
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ovulation, childbirth, erection, ejaculation
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What is gametogenesis and what is a key event?
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production of haploid germ cells by meiosis; key event is crossing over and independent assortment
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What are the two major classes of reproductive hormones?
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androgens and estrogens
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what controls reproductive hormones?
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coordinated action of the hypothalamus-pituitary-gonadal axis - trophic and nontrophic effects
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What are the gonadotropins?
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follicule stimulating hormone (FSH) and luteinizing hormone (LH) - both produced by anterior pituitary in response to gonadotropin releasing hormone
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what do gonadotropins trigger?
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synthesis of androgens and estrogens; tend to have synergistic effects
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What are the key cells involved in oocyte generation?
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follicle cells, granulosa and thecal cells
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what does follicular atresia do?
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cause the degradation of 99% of all germ cells
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what is responsible for the female reproductive cycle?
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fluctuations in levels of gonadotropins and estrogens
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what do granulosa cells do?
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produce estrogens
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what do thecal cells do?
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produce androgens
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What happens in oogenesis that is unique?
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only a single gamete is produced, the other division becomes an inactive polar body which degenerates
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what is a graffian follicle?
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structure in the ovary where the ovum develops before ovulation
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what is the menstrual cycle and what is it regulated by?
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coordinated changes in the ovarian follicle development and uterine lining thickening; regulated by changes in circulating gonadotropins and estrogens
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what is the follicular phase?
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day 1 of menstruation to ovulation; development of a Graffian follice; early rises in FSH and LH; FSH promotes follicle development; follicles produce estrogens; estrogen inhibits FSH and LH release
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What is the early/mid follicular phase?
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dominant follicles produce high amounts of estrogen which act via negative feedback on the HPG axis; granulosa cells produce inhibin which cause a drop in FSH levels
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what happens at follicular phase?
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at high estrogen inhibition of LH stops and positive feedback begins, high estrogen levels increase LH secretion which increases estrogen; estrogen increases granulosa LH receptors
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what happens during ovulation?
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LH surge triggers ovulation and begins luteal phase, ruptured follicule becomes corpus luteum, secretes estrogens and progesterone
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what happens during the luteal phase?
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CL produces estrogens and progesterone but only for 10 days if not fertilized, then degrades; WithoCL becomes scar tissue called corpus albicans; plasma estrogens and progesterone fall leading to the menstrual phase
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what happens after the luteal phase if fertilization occurs?
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CL does not degrade and estrogen and progesterone levels remain high
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what are the 3 phases of the uterine cycle?
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menstrual, proliferative, and secretory
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what happens during the menstrual phase in the uterine cycle?
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caused by falling estrogen and progesterone levels; constriction of outer endometrial blood vessels reduces blood flow and tissues die and detach from the uterine walls
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what happens during the proliferative phase in the uterine cycle?
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caused by a rising estrogen levels from developing follicles in the ovary; endometrial lining tissue begins to regenerate and rethicken, vasculature reforms
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what happens during the secretory phase of the uterine cycle?
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caused and maintained by high progesterone from the corpus luteum; fully formed endometrium secretes glycogen creating a cervical plug; no fertilization causes the loss of corpus luteum and triggers menstruation
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where does spermatogenesis occur?
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seminiferous tubules of the testes
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what are the major cells involved in spermatogenesis
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sertoli and leydig cells, spermatocytes
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what do Leydig cells do?
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produce androgens (like thecal cells)
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what to Sertoli cells do?
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nourish developing sperm and produce binding proteins (support cells for spermatocytes); they are joined by tight epithelium to form the blood testis barrier
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what do spermatoctyes develop from?
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spermatogonia: undifferentiated stem cells which propagate via mitosis prior to meiotic division
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what happens to the daughter cells in spermatogenesis?
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only one goes through meiosis, the other is stored as a stem cell
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what are the three regions of the sperm?
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head, midpiece (provides ATP for tail movement and anchors tail), tail
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what is the acrosome
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found in head of sperm, contains fertilization proteins
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what are the accessory glands to spermatogenesis?
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seminal vesicles, prostate, bulbouretheral gland
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what do the seminal vesicles do?
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secrete basic fluid, clotting proteins, and prostaglandin; make up 60% of semen volume; neutralizes vaginal acidity and binds sperm together to allow them to travel as far as they can
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what does the prostate do?
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secrete citrate which is used as energy for tail movement and enzymes which break down clotting factors
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what does the bulbourethral gland do?
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produce lube prior to ejaculation, helps to lubricate the urethra
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what do the male gondotropins do?
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nontropic FSH effects: stimulates first division of meiosis during spermatogenesis and increases androgen binding protein expression in Sertoli cells; non tropic LH effects: tropic effects only, acts on Leydig cells
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what do Sertoli cells do?
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produce inhibin to stop FSH production
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what do androgens do?
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stimulate spermatogenesis, promote development of secondary sex characteristics, increase sex drive, promote protein synthesis, stimulate growth hormone, promotes developemt of male reproductive system
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what are the steps of an erection?
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activated by short spinal reflex and long input from the brain, reduces SNS and increases PNS, neural vasodilation and nitiric oxide release; positive feedback of pressure on veins due to increased blood volume
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what are the steps of ejaculation?
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spinal reflex that activates the SNS innervates the accessory glands, triggers contraction of the epididymis and vas deferens, and secretions of the prostate and seminal vesicles
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how long can sperm live in the reproductive tract vs. oocytes and why?
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5 days vs 24hrs because sperm need to be present for a few hours before they can fertilize (capacitation)
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what is capacitation?
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occurs after a few hours of sperm in reproductive tract, sperm changes tail movement to increase speed and there are alterations in the acrosomal membrane
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where does fertilization usually occur
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uterine tubes
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what are the steps of fertilization?
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sperm pushes through corona radiata and zona pellucida, then bind to sperm binding proteins in the zona pellucida; sperm binding activates acrosomal reaction releasing enzymes that degrade the zona pellucida and the first sperm binds to a receptor which cases its transport into the cell
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what's wrong with polyspermy?
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leads to chromosome aberrations
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when does implationation occur and what occurs?
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a week after fertilization; a trophoblast invades the endometrium of the uterus
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what is the decidual response?
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trophoblast secretes paracrine signals that act on the nearby endometrial lining increasing capillary proliferation resulting in specific tissue appearance of the maternal placement region
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what is inside the stratum functionalis?
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decidua placentalis, parietalis, and capsularis
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what happens in pregnancy to the corpus luteum?
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hCG (gondotropin) maintains the corpus luteum during the first trimester, after 3 months the placenta takes over production of estrogen and progesterone
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what does estrogen do in pregnancy?
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increases breast duct tissue growth, prolactin secretion and growth of uterine smooth muscle for parturition and lactation
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what does progesterone do in pregnancy?
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stimulate breast glandular tissue, inhibits uterine contractions and maintains the secretory phase of the uterine lining
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what happens during puberty?
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prepubescent individuals have an inactive HPG axis, the onset of puberty starts with a high hypothalamic GnRH relrease, a large increase in sex steroids leads to development of secondary sex characterisitcs
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