2. 11/09 F + E Flashcards
- antr pit gland
produces follicle stimulating hormone and leutinising hormone which influences the 3 phases of the ovarian cycle and the menstrual cycle.
primary hormones secreted by hypothalamus
- corticotrophins releasing hormone (CRH)
- gonadotrophin releasing hormone GnRh
- growth hormone releasing hormone GHRH/GH inhibiting hormone GHIH aka somatostatin
- prolactin releasing hormone / prolactin inhibiting hormone PIH aka dopamine
- thyrotropin releasing hormone TRH
- anti diuretic hormone ADH and oxytocin
reproduction cycle phases + locations
pituitary; brain
ovarian; ovaries
menstrual; uterus
pituitary cycle
- Hypothalamus receives positive feedback and releases GnRH to anterior pituitary, either releases FSH or LH depending on stage of menstrual cycle.
- FSH —> Graafian follicle.
- Oestrogen produced, negative feedback to antr pit. Antr pit stops producing FSH and starts LH, GF ruptures and ovulation occurs. /
- Egg released and looking for sperm, LH increases.
- LH —> CL formed, producing estrogen and progesterone, preparing for implantation, however if no implantation the CL degenerates, causing menstruation.
Graafian follicle development
primordial follicle, early primary follicle, late primary follicle, secondary primary follicle, Graafian follicle (FP) , rupturing follicle (O) corpus luteum (LS), corpus albicans.
ovarian cycle
- follicular/proliferative phase
- ovulation
- luteal/secretory phase
follicular/proliferative phase
- follicles enlarge and one matures, or ripens, each month (Graafian Follicle).
- graafian follicle swells and becomes tense.
- oestrogen dominant.
ovulation
- releases ovum into fimbulated end of uterine tube.
luteal/secretory phase
- cells of the ruptured follicle proliferate to make structure irregular in shape and yellow in colour ‘Corpus Luteum’
ovarian hormones which influence reproduction cycle
oestrogen, progesterone, relaxin
oestrogen effect on repro cycle
- inhibits FSH release so only one egg matures in a cycle.
- stimulates the pituitary gland to release the hormone LH.
progesterone effect on repro cycle
- acts on the endometrium to prepare for implantation.
- raises body temperature by 0.5°C after ovulation and causes tingling and sense of fullness of breasts prior to menstruation.
relaxin influence on repro cycle
- small amounts cause uterine quiescence which is the ideal environment for fertilised oocyte to implant.
repro cycle summary; follicular
FSH stimulates growth of several follicles, dominant follicle secretes oestrogen, oestrogen inhibits growth of other follicles (and FSH), oestrogen stimulates development endometrium
repro cycle summary; ovulation
surge in LH causes ovulation, rupturing of follicle creates corpus luteum
repro cycle summary; luteal
CL secretes P+E, P stimulates development of endometrium
E + P inhibit FSH + LH, CL degenerates over time, CL degrades and P levels drop
without P, endometrium cannot be maintained so endometrium is sloughed away -menstruation
no longer inhibited, FSH can start menstrual cycle again
if fertilisation occurs, the zygote releases a hormone hog which maintains the CL.
corticotrophin releasing hormone CRH
stimulates ACTH release from antr pit
gonadotrophin releasing hormone GnRH
stimulate FSH and LH release from antr pit
growth hormone releasing hormone GHRH/GH inhibiting hormone GHIH aka somatostatin
stimulate growth hormone GH/GHIH release from antr pit
prolactin releasing hormone/prolactin inhibiting hormone PIH aka dopamine
stimulate prolactin release from antr pit
thyrotropin releasing hormone TRH
stimulate TSH release from antr pit
anti diuretic hormone ADH and oxytocin
post pit hormone
ovulation monitoring
- calendar method
- basal body temperature (progesterone causes temp spike)
- billings method/family planning
- ovulation strip
- ovulation Cassette
- ovulation microscope
- intake of Alkaline food
indication by cervical mucus
- cervical mucus test; 12-14 days of cycle. The mucus increases in amount in the preovulatory estrogen dominated phase; watery, clear, copious, acellular, excellent spinnberkeit>8cm long , has fan pattern when dried.
- 13-14 day egg yolk signifies ovulation will occur in the next couple hours.
- cervical mucus decreases in amount, changes in character, no longer dries in a fan pattern in the luteal phase.
spermatogenesis
- start at puberty.
- production under the effect of LH&FSH.
- LH stimulate the production of testosterone from the testes.
- some testosterone comes from adrenal gland above the kidney.
- stored at epididymis for maturation and motility.
- takes an average of 74days {60-80days}.
- men may produce between two milliliters and five milliliters of semen each time they ejaculate, and that each milliliter may contain from 20 million to 300 million sperm cells.
fertilisation
- fertilisation (conception) is fusion of genetic material from male gamete (sperm) and female gamete (oocyte) which forms diploid zygote (fertilised cell).
- process takes approx. 12-24hours.
- normally occurs in ampulla of uterine tube.
- the oocyte is moved along the tube by cilia, at the same time, the cervix, which is under the influence of oestrogen secretes a flow of alkaline mucus that attracts sperm.
development of zygote
1 - pre embryonic period; fertilisation to week 2 (zygote)
- 2nd week development
- implantation
2 - embryonic period; week 2 to 8 (embryo)
- 3rd week development
- trophoblast
1 - pre embryonic period; fertilisation to week 2 (zygote)
- 2nd week development
- the second week of development is known as the week of twos:
- the trophoblast differentiates into two layers, the cytotrophoblast and
syncytiotrophoblast.
- the embryoblast forms two layers, the epiblast and hypoblast.
- the extra embryonic mesoderm splits into two layers, the somatopleure and splanchnopleure. And two cavities, the amniotic and yolk sac cavities, form.
1 - pre embryonic period; fertilisation to week 2 (zygote)
- implantation
- implantation occurs at the end of the first week.
- zona pellucida degenerates.
- enzyme secreted by trophoblast cells digests decidua cells of endometrium.
- blastocyst enters into the spongy layer of the decidua and becomes
embedded - embedding is also termed nidation (nesting). - embedding complete by day 11 following ovulation.
- the only evidence of the presence of the blastocyst is a small bulge on the surface of the decidua.
2 - embryonic period; week 2 to 8 (embryo)
- 3rd week development
- third week of gestation is gastrulation, the process that establishes all three germ layers (ectoderm, mesoderm, and endoderm).
- gastrulation begins with formation of the primitive streak on the surface of the epiblast.
primitive streak
ectoderm - Brain, spinal cord, skin
mesoderm - skeleton, muscles, kidneys, heart
endoderm - GI tract, lungs
2 - embryonic period; week 2 to 8 (zygote)
- trophoblast
Trophoblast (outer cells of blastocyst) develops chorionic villi:
- chorionic frondosum - placenta
- chorion leave – chorionic membrane
Trophoblastic cells differentiate:
- syncitiotrophoblast
- cytotrophoblast
- mesoderm
devlopment of zygote
egg,
zygote,
2 cell stage,
4 cell stage,
morula,
blastocyst,
embryoblastocyst,
trophoblast
