pregnancy physiology part 1 Flashcards
when must fertilisation occur after ovulation?
24 hrs
where does fertilisation occur?
Fallopian tube
how is a blastocyst formed?
through division of zygote
where does a blastocyst implant?
in the wall of the uterus-endometrium
what are the two layers of the uterus?
outer muscular layer- myometrium
inner layer- endometrium
what cells form the placenta during implantation?
trophoblasts
what finger-like projects are found in the placenta?
placental villi-chorionic tissue
what are the placenta villi surrounded by?
maternal blood
how are metal blood and maternal blood seperated?
by capillary wall
where does the maternal blood enter to exchange with fetal blood?
intervillus spaces of placenta villi
do maternal and fetal blood mix?
no
what systems does the placenta function as? and is this controlled by the foetus itself or the mother?
digestive, respiratory and kidneys and controlled by the mother
what sort of placental diffusion occurs for things like water, electrolytes, 02 etc?
simple
what sort of molecules require active transport?
glucose and amino acids
how is cholesterol transported across placenta?
receptor-mediated endocytosis
what may cause harm to the foetus if crossed via placenta?
drugs
alcohol
thalidamide
smoking
aids
what else does the placenta act as?
endocrine gland
what is the purpose of placental hormones?
to maintain the pregnancy
what placental hormones are produced?
-hCG
-estrogen
-progesterone
what hormone is detected by pregnancy tests?
hCG
when does hCG rise in pregnancy?
early pregnancy then drops
what is the purpose of the rise in hGC in early pregnancy?
prolongs the life span of corpus luteum
what is the purpose of corpus luteum?
produces oestrogen and progesterone
what stimulates testosterone release in males?
hCG
how many weeks in hCG and corpus luteum needed?
around 10 weeks then the placenta can form oestrogen and progesterone on its own
why is the placenta unable to produce oestrogen in early pregnancy?
it does not have the specific enzymes needed
why is the placenta unable to produce progesterone in early pregnancy?
the placenta is too small to make enough
how is oestrogen formed in the placenta?
cholesterol makes DHEA which forms oestrogen by adrenal cortex
how is progesterone formed in the placenta?
from cholesterol
what is the purpose of E and P in maintaining the pregnancy?
it allows the maintenance of thick endometrial tissue and stops menstruation
what are the two purposes of estrogen?
-growth of myometrium
-growth of mammary milk ducts (milk ejects)
what are the 3 purposes of progesterone?
-prevent miscarriage by preventing myometrium contractions
-stop vaginal contamination
-stimulates milk glands in breasts
