reproductive physiology Flashcards
male reproductive tract: significance of urethra
testis (sperm produced) -> ductal system -> connects to same outflow tract (urethra) as urinary system; other glands (e.g. Cowper’s, prostate), seminal vesicles
4 regulatory hormones of reproduction and location of release
GnRH (hypothalamus), LH and FSH (anterior pituitary), testosterone (testis)
main regulatory pathways withn adult male reproductive system: LH
hypothalamus -> GnRH (pulsatile) -> anterior pituitary -> LH to Leydig cells (only cells expressing LH receptors) -> testosterone (negative feedback to anterior pituitary and hypothalamus) -> primary tole in spermatogenic cells in seminiferous tubule for gamete production (has other roles) -> Sertoli cells release inhibin (negative feedback to hypothalamus)
main regulatory pathways withn adult male reproductive system: FSH
hypothalamus -> GnRH (pulsatile) -> anterior pituitary -> FSH to spermatogenic (Sertoli) cells in seminiferous tubule which regulates function and enhances production of sperm -> Sertoli cells release inhibin (negative feedback to hypothalamus)
anaotmy of spermatogenesis
testis, epididymis, seminiferous tubules
cells on outer layer of seminiferous tubule
Sertoli cells
process of spermatogenesis (very rapid and imperfect process, but enough normal ones produced to fertilise an egg)
primordial germ cell (46 chromosomomes) -> spermatogonium -> (mitotic division) -> primary spermatocyte -> (1st meiotic division) -> secondary spermatocyte -> (2nd meiotic division) -> spertmatids -> mature sperm (23 chromosomes: 22X and Y, or 23X)
contents of mature sperm
acrosome, sperm head, spermatid cytoplasm
when does male and female reproductive function start
puberty
duration of male reproductive function
continually throughout rest of life
what happens to sperm with increasing age
sperm quantity and quality generally decrease
what does LH stimulate in male reproductive tract
testosterone production
what cells do FSH and testosterone sustain in male reproductive tract
Sertoli cell
function of Sertoli cells in male reproductive tract
support spermatogenesis
regulatory and duration of female reproductive function
cyclically until approx 45 y/o
what happens to eggs with increasing age
quality generally decreases
what does FSH stimulate in female reproductive tract
some development of ovarian follicels and 17B-oestradiol synthesis
what does LH stimulate in female reproductive tract
progesterone function
function of 17B-oestradiol and progesterone in female reproductive tract
regulate uterine endometrium
female reproductive system pathway
hypothalamus -> GnRH -> anterior pituitary -> LH and FSH -> ovaries -> progesterone and oestrogen (negative feedback to hypothalamus and anterior pituitary)
female reproductive system pathway: ovarian cycle - follicular phase
hypothalamus -> GnRH -> anterior pituitary -> LH and FSH -> ovaries -> oestrogen (negative feedback to hypothalamus and anterior pituitary)
female reproductive system pathway: ovarian cycle - midcycle
hypothalamus -> GnRH -> anterior pituitary -> rapid peak of LH and FSH (ovulation) -> ovaries -> oestrogen (positive feedback to hypothalamus and anterior pituitary, upregulating GnRH, FSH and LH so huge increases in oestrogen levels)
female reproductive system pathway: ovarian cycle - luteal phase
hypothalamus -> GnRH -> anterior pituitary -> LH and FSH -> ovaries -> progesterone (negative feedback to hypothalamus and anterior pituitary)
describe changes in female circulating hormones during the ovarian cycle
oestrogen peaks just before midcycle, with progesterone and oestrogen high in luteal phase; following peak of oestrogen, have peaks of LH and FSH (accelerate growth of follicle and release egg in ovulation)
changes in endometrium during normal menstrual cycle
endometrium is relatively thin (2-4mm) increases during proliferative and secretory phase to 7-16mm, but in last 3-4 days endometrium is shed in menstruation
what controls menstrual cycle
oestrogen drives early (proliferative) phase, later (secretory) phase driven by oestrogen and progesterone
what causes menstruation
decline in progesterone due to break down of corpus luteum (following ovulation and release of egg, follicle becomes corpus luteum)
describe process of oogenesis
primordial germ cell -> oogonium -> primary oocyte -> secondary oocyte (and first polar body) -> ovum (and second polar body)
describe process of folliculogenesis in ovary (eggs produced in utero, but last stages after puberty)
primordial follicle -> primary follice -> growing follicle -> antral follicle -> ruptured follicle -> following ovulation (in puberty), -> corpus luteum -> degenerating corpus luteum
folliculogenesis (elongated process taking approx. 3 months, with multiple eggs undergoing process in both ovaries at the same time, producing non-identical twins if both fertilised)
resting follicle begins initiation -> basal growth (pre-antral -> early antral) -> recruitable (atresia of other follicles) -> selected (only dominant follicle (s) are ovulated)
define ovulation
release of mature oocyte from ovary
during ovulation, what is the number of chromosomes of the oocyte
2n (hasn’t become haploid), in meiotic arrest (metaphase II)
where does the oocyte enter following ovulation
Fallopian tube
how soon does the oocyte need to be fertilised to prevent degeneration
within 24 hours
what do sperm have to do in order to accomplish fertilisation which filters out malfunctioning sperm
swim up cervix, uterus, and Fallopian tubes to egg, then release acrosome digestive enzymes (make way through cells left by follicle on outside of egg, and zona pellucida of egg, allowing head of sperm to enter cytoplasm of egg), with head contributing male pronucleus (23 chromosomes)
process of fertilisation
as fertilisation occurs, meiotic arrest of egg is removed, so meiosis continues (so instead of 2n structure, is converted to single n gamete to form single female pronucleus and 2nd polar body) -> DNA in both pronuclei duplicates -> form mitotic spindle without a nucleus -> metaphase of first cleavage division -> metaphase of cleavage division 1 -> separation of chromosomes -> 2 nuclei containing one cluster of chromosomes -> 2-cell stage
what happens to maternal chromosomes in oocyte after fertilisation
meiosis of maternal chromosomes resumes, forming female pronucleus (23 chromatids - 23 paired chromosomes) and 2nd polar body
what happens to sperm chromosomes in oocyte after fertilisation
sperm chromosomes decondence to form male pronucleus (23 chromatids - 23 paired chromosomes)
what happens to chromatids in both pronuclei following decondensation
duplication before aligning on mitotic spindle to be separated into 2 identical daughter cells (1st cleavage division of embryo)
