18. Fertilisation 2b Flashcards
- pregnancy - what hormones stay high during pregnancy and what stay low. why?
high - progestron
low - estrogen
prevents uterine contractions during embryo development
- what hormone stimulates ACTH from the pituatary galnd and what does ACTH do?
coricotrophin-releasing hormonme stimulates ACTH.
ACTH stimulation the secretion of cortisol
- pregnancy - what does the increased cortisol do? 2 points
inhbits progestrone from the placenta
increases prostaglandin secretion
- pregnancy - how does prostaglandin get rid of progestrone? how is this important?
it allows for luteolysis (destruction of the corpus luteum)
important for the removal of the last source of progestrone
- pregnancy - what does estrogen stimulate in pregnancy?
stimulates uterine contactions and increased oxytocin - oxytocin + prostaglandin increases the levels of hormones in the blood
- pregnancy what is the feedforward mechanism? what does it do in birth?
oxytocin with prostaglandin is the feedforward mechanism.
it encourages myometrium contraction and dilation of teh cervix for birth
what is mammogenesis?
the growth and development of the mammary glands
what two hormones stimulate mammary duct growth?
high progestrone and low estrogen
why is menstruation possibly a survival trait in humans?
it enables grandmother to help daugther to raise grandchildren - therefore increased survival rate. genes of grandma survive
what are four differences in oestrous cycles from menstral cycles?
theres no menstruation (bleeding)
no menopause
only sexually rceptive during clycle (‘in heat’)
overt ovulation (expressed externally)
give three examples of overt ovulation and what is it caused by
lordosis ref;ex - raising of hindquarters and tail
vuvae reden and swell
odour released
caused by a peak in estrogen concentration
what is the difference in monoestrous, diestrous and polyestrous cycles?
monoestrous - one cycle a year
diestrous - two cycles a year
polyestrous - many cycles a year
name three functions of follicle stimulation hormone
stimilates speratogenesis (males)
stimulates follicle to grow
causes ovaries to secrete estrogen
what are three funcitons of luteinsing hormone
stmulates testoterone production
stimulates final matruation of follicle
develops corpus luteum
what are three funcitons of estrogen?
stimulates sexual receptivness (arousal)
further stiulates lutenising hormone secretion
stimulates endometrium to grow
stimulates mammogenesis
inhibits GnRH release (prevents cycle)
