reproductive physiology Flashcards
identify the parts of the male reproductive tract *
teh ductal system goes from the testes and connects to the same tract as urine
both the urine and seminal fluid/ejaculate come out of the urethra
describe the endocrine regulation of the male reproductive tract *
GnRH is released from the hypothalamus - pulsitile
it acts on the anterior pituitory - ant pit produces LH and FSH which work together to cause the production of testosterone from the testes
LH acts on the leidig cells only - the leidig cells make testosterone
testosterone enters the seminiferous tubule and helps with the production of sperm (testosterone has other effects too)
FSH acts on the sertoli cell in the seminiferous tubule - they produce antigen binding protein (ABP)
ABP binds testosterone and regulates the function of sertoli cells and enhances the production of sperm
sertoli cells release inhibin which inhibits LH and FSH release
testosterone also has -ve feedback effect on LH/FSH
describe spermatogenesis *
happens in the seminiferous tubule
germ cell becomes sperm cell through mitosis to keep up the numbers, and meiosis to form haploid cells
- diploid spermatogonium (germ cells) are near the basement membrane
- undergo mitotic division = primary spermatocyte
- 1st meiotic divison = secondary spermatocytes (haploid)
- 2nd meiotic division
- spermatids
- spermatazoa
- released into the lumen of the seminiferous tubule
- journey along the epididymis, vas deferens and urethra
summarise the male reproductive function *
starts at puberty
functions continually
continues throughout life normally
sperm quality and quantity decrease with age
LH stimulates testosterone
FSH and testosterone sustain sertoli cell function
sertoli cells support spermatogenesis
problem with the rate of production of sperm *
it is a very rapid process
likely to be a lot of msitakes
only 4% sperm are ‘normal’ this is enough because so many are produced
summarise the female reproductive function *
starts at puberty
functions cyclically - 28-30 days
normally operates until 45yrs - varies
egg quality decreases with age - more likely to have abnormalities eg chromosomal abnormalities
FSH stimlates (some) development of ovarian follicles and 17B-oestadiol synthesis
LH stimulates progesterone production
these steroids regulate uterine endometrium
summarise the hyopothalamo-pituitary-gonodal axis for females *
LHRH (also called GnRH) released from hypothalamus
acts on ant pit = production of LH and FSH
LH and FSH act in ovaries
ovaries produce progesterone and oestrogen that act in the uterus
prog and oest provide -ve feedback on hyp and pit
what are the 3 phases of the ovarian cycle and the hypothalamus-pituitary axis in them *
follicular - oestrogen provides -ve feedback - shuts down the reproductive axis
midcycle - oestrogen upregulates production of GnRH and LH FSH because the hyp and pit’s sensitivity to oestrogen has changed = further production of oestrogen - it is a feedforward loop
luteal phase - after ovulation progesterone is the main hormone - this provides -ve feedback
describe the levels of hormones through the ovarian cycle *
peak of oestrogen just before midcycle, blip of progesterone
peak of LH and FSH at midcycle - accelarates the growth of the main follicle and release of egg
both progesterone and oestrogen high in luteal phase - progesterone is higher
combination of oestrogen and progesterone regulates the menstrual cycle and uterine function
key hormones in the release of the egg
describe the menstrual cycle *
under the control of steroids
oestrogen causes early growth
in the 1st 2 weeks the follicule develops and produces oestrogen - causes thickening in 1st phase - proliferative/follicular phase
then there is ovulation making the egg
corpus luteum is left behind - this makes progesterone and oestrogen
uterine wall is thick for implantation by progesterone and oestrogen in 2nd phase - secretory/luteal phase - 7-16cm
the sharp fall of progesterone at the end of the luteal phase is what causes bleeding over 3-4days go back to 2-4cm
describe oogenesis *
go from primordal germ cell to oogonium to primary oocyte in utero
then from primary oocyte to secondary producing polar bodies at puberty
this is a reason why quality decreases as women age as there is a longer gap from the start of the process makling primary oocyte to end of the process
describe folliculogenesis *
primordal follicle (containing a primary oocyte), primary follicle, growing follicle, antral follicle (has antrum in it), ruptured follicle - ovulation and a secondary oocyte, corpus luteum, degenerating corpus luteum
in last stages of development before ovulation the follicle produces oestrogen
corpus luteum produces progesterone and oestrogen
describe the time frame of folliculogenesis *
initiation phase - the resting oocyte is present more than 2 cycles before the egg is ovulated
basal growth - follicle becomes pre-antral, then early antral
towards end of the 2nd cycle the follicle is recruitable and then is selected for rapid growth at early 3rd cycle
what is ovulation *
release of mature egg from the ovary at midpoint of the menstrual cycle - approx day 14
what is the state of the oocyte at ovulation *
2n - it is in meiotic arrest at metaphase II
it then enters the fallopian tube
describe fertilisation *
occurs in fallopian tube
needs to happen within 24hrs otherwise the egg degenerates after this and sperm dont last long outside the male either
sperm is deposited at cervix - mucus of cervix is normally hostile to the sperm, mucus changes midcycle allowing sperm to enter the uterus
capicitation occurs in uterus
sperm passes into fallopian tube - go to ampulla
acrosome is a package of enzymes to digest the zona pollida and make way through cells left from follicle - allows DNA to enter the egg - chromosomes decondense into the male pronucleus
Ca flux
the meiotic arrest is removed and meiosis of the female egg continues - becomes haploid (23 chromatids) - get female pronucleus and 2nd polar body
change in the ZP to stop other sperm entering - this is the cortical reaction - other sperm and cumulus cells are present but dont contribute anymore
the chromatids in both pronuclei are duplicated and align on the mitotic spindle - metaphase plate is formed
the spindle pulls the chromosomes apart
each cluster of chromosomes forms a nucleus - this is now an embryo with 2 identical daughter cells
mitotic divisions
what is the difference between post-ovulation and post-fertilisation time frames *
24hrs
fertilisation has to happen within 24hrs of ovulation
main functions of the male reproductive system
to make mature sperm
provide andrognes to initiate and sustain the male phenotype
describe testes *
they contain seminiferous tubules which produce sperm, and leydig cells (interstitial cells) which produce testosterone and other androgens
describe the epididymis *
there is one in each scrotal sac - they connect the testes top the vas deferens
sperm are released from the testes and stored here prior to ejaculation
describe the pathway of sperm *
released form the testes
stored in the epididymis
at ejaculation the sperm pass through the 2 vas deferens (which are contractile) and are mixxed with fluid from seminal vesicles
the fluid then leaves the ejaculatory duct and passes into the urethra where it mxes with secretions from the prostate gland
role of the female reproductive system *
produce steroids (progesterone and oestrogen) to maintain female phenotype and produce oocytes - this happens in ovaries
uterus involved in reproduction
describe teh fallopian tube *
it is how the oocyte reaches the uterus
provides an appropriate env for an oocyte or conceptus
do all follicles develop to ovulation *
no - atesia is common
what are the thecal cells
they are part of the follicles
responsible for the production of oestrogens
what do the granulosa-luteal cells produce *
oestrogens and progesterones during the 2nd half of the ovarian cycle
how does the length of the menstrual cycle vary through life *
when young, shortly after menache - may be 45 days
just before menopause can get shorter/longer, may miss a couple and resume
describe the connections between the ovarian and endometrial cycle *
phases of the endometrial cycle *
menstrual phase - 5days
- shed blood - remaining basal endometrium is very thin
repair and proliferative phase - 9 days
- stimulation of endometrial proliferation
- increase in thickness, number and length of glands, length of arteries
secretory phase - 13days
- production of nutrients and other factors
- epi glands widen, endometrium thickens, increased coiling of spiral arteries
when does the body temperature rise in the menstrual cycle *
ovulation
describe oogenesis including the time frames of the divisions *
- oogonia (diploid)
- mitotic division = primary oocytes
- 1st meiotic division during formation of the secondary follicle = secondary oocyte and 1st polar body - diploid - there is a pause in this meiosis at the siplotene stage of prophase 1 until puberty
- 2nd meiotic division - stops in metaphase 2 until fertilisation
time taken to go from primordal follicle to secondary oocyte >1month
ovaries contain many follicles at various stages at any 1 time - the dominant follicle enters the later stages to form the secondary (Graafian)
ovaries usually alternate between release of a follicle
human ovaries contain 2million primordial follicles at birth, only 400 will be released at ovulation during a reproductive lifetime
most important role of sex
ensure fertilisation of a mature oocyte by a mature sperm
define sexual reproduction *
produces offspring that differ genetically from both parents
define sexula intercourse *
required for sexual reproduction (usually), activity, pleasure and human bonding
define biological sex *
identifies gender, results from the chromosomes, depends on the production of gametes
describe the links in the brain between parenting, fertility, reward and pleasure *
human bonding is linked to reproduction and parenting
the nigrostriatal tract controls movement
the mesolimbic dopaminergic system is involved in pathways for reward and pleasure
activation of the pleasure pathway encourages intercourse and so the continuation of human race
describe the brains contriol of erection *
via the spinal cord and efferent nervous system
(tactile stimulus of the penis can activate the affernet system [pudendal nerve] = more direct interaction between the spinal cord and the penis)
there is increased PNS activity to sm of pudendal artery = increase in NO sythase = increase in NO
NO increases cGMP = dilation of arterial sm - thsi counteracts the sympathetic mediated myogenic tone = incleased blood flow into the corpus cavernosum = compression of the dorsal vein - restricting outflow of blood
the urethra is protected from the increasing pressure by the corpus spongiosum
cGMP is inhibited by phosphodiesterase (viagra inhibits phosphodiesterase)
describe the brains control of the cliteris *
same process as the penis = increased size
