Reproduction and Sex Steroid Axis - unfinished Flashcards
what is the mean duration of the menstrual cycle
28 days
ranges from 21-35
average duration of menses and estimated blood loss
3-5 days
30ml
when in the menstrual cycle does ovulation usually occur
mid cycle eg day 14
describe follicular growth
begins when oestrogen levels are low, this provides feedback stimulating the anterior pitutiary to secrete LH and FSH stimulating follicles to develop
one leading follicle develops
the granulosa around the egg enlarge, and release oestrogen - this causes the lining of the uterine to thicken
what hormone is responsible for the recruitment of the dominant follicle
FSH
describe the ovulation phase
occurs at peak follicular growth in response to a surge of LH
follicles grow to at least 20mm in size before they can release an egg. LH and FSH continue to be released for 3-4 days, and LH continues further in response to oestradiol
after the peak in LH, the oocyte is released. the collagen wall of the follicle is digested by proteolytic enzymes and prostaglandins and rupture releasing the ova into the fallopian tubes
describe the luteal phase
the secretory phase that starts after ovulation
beigns with the formation of the corpus luteum from the remaining granulosa cells
this releases progsterone by the action of 3ß- HSD
peak progesterone productionis noticed one week after ovulation takes place
why is the corpus luteum yellow
due to keratin
describe menstruation phase
in the absence of pregnancy, the CL disintegrates (luteolysis) and progesterone levels drop, the uterine lining detached adn menstruation begins
what is in the discharge during menstruation
tissue, blood and unfertilized egg
what is the suspensory (IP) ligament
attaches the ovary to pelvic side wall
describe the ovary
has an outer cortex and inner medulla
the cortex contains the follicles
describe the uterus
fibromuscular organ, conatins the body of the uterus and the cervix
the endometrium has a basal and superficial layer, and thickens in response to oestrogen release
if there is a lack of hCG and progesterone (CL), the endometrium sloughs off
what is GnRH produced by
arcuate nucleus in the hypothalamus
GnRH
deca peptide hormone
there are 3 types: GnRH 1 is responsible for reproductive function
it is released in a pulsatile manner and has a half life of 2-4 minutes
FSH
glycoprotein that contains 2 subunits, and has a half-life of several hours
it is responsible for recruiting the dominant follicle, granulosa cell growth and the activation of aromatase activity
LH
acts on the theca cells
responsibel for the uptake of choelsterol and the conversion of androgens to oestrogens
inhibin
local peptide found in the follicular fluid
down regulates FSH secretion and locally enhances LH induced androstenedione production
what are the tubular components of the testis
sertoli and germ cells
describe the development of spermatogonium to spermatozoa
a spermatogonium is an undifferentiated male germ cell
describe the first steps in maturation of a sperm cell
excess cytoplasma and material in cells is eaten up by Sertoli cells
tails begin to develop and DNA is repackaged
the sperm cell has an acrosome and a tail (required for motility)
acrosome
sperm has an acrosome that conains digeestive proteins that are rquired to digest the egg’s outer shell (zona pelludica) allowing haploid nucleus in sperm cell to join haploid nucleus in ovum
