the dreaded repro. Flashcards
describe the covering of the testes.
tunica alberguinea is a thin fibrous semi-covering. tunica vaginalis (viceral) then tunica vaginalis (parietal) then internal spermatic fascia, cremaster fascia, and external spermatic fascia.
why is thermoregulation required?
optimum temp for spermatogenesis is 35 degrees so heat is transferred from the testicular arteries to the pamniform plexus of veins.
what is spermatogenesis?
differentiation of spermatids to spermatozoa. there is a loss of cytoplasm and a tail forms.
describe the full maturation of sperm from spermatogonium to spermatozoa.
spermatogonium differentiate into type A or type B spermatogonia. type A continue to produce daughter cells and do not pass through the blood testes barrier. and do not differentiate further. type B differentiates into a primary spermatocyte and then divides to form secondary spermatocytes. these then divide to form spermatids. these spermatids then undergo spermatogenesis to form spermatozoa.
what is the function of sertoli cells?
they form the blood-testis barrier, they are supporting cells for the sperm and they remove debris etc.
what is the acrosome?
acts as a spermatic head. releases acrosomal enzymes in the breakdown of the zone pellucida
why are mitochondria needed?
flagellar movement.
what are the other parts of a mature sperm?
axoneme = cytoskeletal structure. the principal piece is the bulk of the tail and it is the axoneme surrounded in a membrane. the end piece is bare axoneme
describe the drainage of the testes.
the seminiferous tubules join together to form the rete testes. the rete testes drain into the 12 small ducts and they drain into the epididymus.
how long can the epididymus hold sperm for? what is its histology?
40-60 days. long columnar epithelium with a prominent brush border
describe the anatomy of the vas deferens.
30cm muscular tube. shorter columnar epithelium. peristalisis. widens at its terminal called the ampulla.
what is normal sperm count? what is infertility?
50/100 mil.
how many sperm are made per minute?
300-600
how long does spermatogenesis take?
64 days.
what gene determines sex?
SRY
in the absence of Y, how does the foetus develop?
the wolffian duct regresses in the absence of testosterone. Oestrogen production stimulates the differentiation of the mullein duct. the mullerian duct forms the cervix, the uterus, upper vagina, and the fallopian tubes.
when does differentiation begin?
6 weeks
If the Y gene is present, how does the foetus develop?
the mullein duct regresses in the absence of oestrogen. testosterone production stimulates the differentiation of the wolffian duct into the epididymus, the vas deferens, seminal vesicles and the ejaculatory duct. the testes develop on the posterior abdominal wall then migrate through the inguinal canal and into the scrotum.
what happens hormonally wise during puberty?
hypothalamus starts secreting high levels of GnRH which in turn increases LH and FSH. levels of GHRH also significantly rise which increases growth.
explain the LH surge.
FSH secretion is inhibited by oestrogen. At the start of the menstural cycle there is no oestrogen being secreted, therefore FSH secretion increases. this stimulates growth of the follicles. As the follicle grows, it starts to secrete oestrogen, therefore FSH secretion starts to be inhibited. as Oestrogen concentration steadily rises it hits threshold and oestrogen starts feeding back positively. this switch increases the GnRH receptors on the anterior pituitary and therefore there is a surge of LH.
give examples of cardiovascular changes to a woman during pregnancy.
increased cardiac output, dilation of capillaries, reduced total peripheral resistance, varicose veins due to backlog.
give some non-cardiovascular related physiological changed that a woman experiences during pregnancy.
linea nigra, stria gravidarum, acid reflux, darkening of nipples, increased alveolar ventilation, formation of mucous plug prior to labour, metabolism decreases.
what is the name for the birth process?
parturition.
what hormone is involved in pre labour?
prostaglandins.
outline the physiology behind contractions.
oxytocin is the main stimulator of contractions. oxytocin from the hypothalamus starts the contractions. this in turn increases the number of prostaglandins, which are also potent stimulators of smooth muscle contraction. this causes the uterus to stretch, which positively feeds back to increase contractions and oxytocin release.
why are there no contractions during pregnancy?
because progesterone is a very powerful inhibitor and suppresses the endometrium’s sensitivity to oestrogen, prostaglandins and oxytocin.
what are the actions of oxytocin? what stimulates its release?
allow lactation and stimulate contractions. suckling and stretch of the uterine wall. triggers ‘caring’ reproductive behaviour.
what does the corpus luteum secrete?
progesterone, oestrogen and inhibin.
why is the negative feedback loop with FSH and oestrogen important?
because a low level of FSH can only support one follicle, this follicle becomes the dominant primordial follicle and continues to develop.
which cells do FSH stimulate?
granulosa
which cells do LH stimulate?
theca.
what are the functions of progesterone?
prevent contractions and miscarriage. thickens endometrium to support placenta.
what are the functions of oestrogen?
produced throughout pregnancy. regulates levels of progesterone. prepares the uterus for baby and breasts.
what are the functions of prolactin?
prevents ovulation. increase cells that produce milk.
what are the functions of relaxin?
ripens the cervix in preparation for delivery. high in early pregnancy.
what are the functions of prostaglandins?
induce contractions.
what are the functions of hCG?
stimulates oestrogen and progesterone production by the ovary. diminishes once the placenta has formed.
what are the pregnancy land marks?
missed period. feral ultrasound = 5/6 weeks. quickening movements = 20 weeks. as pregnancy continues, symphisio-fundal height increases.
give an outline of the menstrual cycle.
day 1-7 = menstruation. day 4-14 = proliferation of the endometrium. day 14 = ovulation. day 15-28 = secretory phase. day 26-28 uterine wall detaches in preparation for menstruation.
how is the transport of sperm aided?
movement of the uterine walls due to prostaglandins and sperm motility from the flagellar tail.
what is capacitation?
the penultimate step in maturation of spermatozoa. During capacitation, the movements of the tail are modified so they are more ‘whip-like’ and less ‘wave-like’. this propels the sperm towards the egg. it can only happen in uterine conditions because the uterus secretes sterol-binding albumin, lipoproteins and proteolytic enzymes
describe the process of fertilisation.
The sperm reaches the egg and has to travel through the granulosa cells and the corona radiata. it reaches the zone pellucida
what enzyme converts
5 alpha reductase. dihydrotestosterone
