Pregnancy Physiology Flashcards
where does fertilisation most commonly occur
ampulla
when is the blastocyst transported to the uterus
days 3-5
when does the blastocyst implant in the uterus lining
day 5-8
what do the inner cells of the blastocyst become
the embryo
what do the outer cells of the blastocyst become
the placenta
what cells help the blastocyst penetrate + adhere to endometrium?
trophoblastic cells
by what day is the blastocyst fully buried in the endometrium
day 12
what is the placenta derived from
trophoblast + decidual tissue
how are placental villi formed
trophoblasts differentiate into synctiotrophoblast- invade decidua + break down capillaries – forms cavities
Developing embryo sends capillaries into these projections- placental villi formed
when is the placenta + foetal heart functional by
week 5
what is the role of HCG in the nutrition of the foetus
signals corpus luteum to continue secreting progesterone-
this stimulates decidual cells to concentrate glycogen, proteins + lipids
which vessel delivers oxygen rich blood to the foetus
umbilical vein
which vessel returns oxygen poor blood back to the mother
uterine veins
which 3 factors facilitate oxygen transport in fetal blood
- fetal Hb- Increased ability to carry oxygen
- higher Hb concentration in fetal blood
- Bohr effect, fetal Hb can carry more oxygen in low pCO2 than in high pCO2
what are the only electrolytes that can go from mother to child
iron + calcium
how does glucose cross the placenta
simplified transport
drugs that can cross placenta and harm the baby
alcohol nicotine heroin cocaine tetracyclics thalidomide carbamazepine
role of HCG
prevents degeneration of corpus luteum
when is HCS (human chorionic somatomamotrophin) produced
from week 5
role of HCS
protein tissue formation
decreases insulin sensitivity in the mother- more glucose for the foetus
involved in breast development
function of progesterone
development of decidual cells
decreases uterus contractility
preparation for lactation
function of oestrogen
enlargement of the uterus
breast development
relaxes ligaments
what affect does the placenta releasing CRH have on the mother
increases ACTH- increases aldosterone
therefore increased cortisol
what does increased aldosterone cause
hypertension
what does increased cortisol cause
oedema
insulin resistance - gestational diabetes
what effects does the placenta increasing calcium demand have on the mother
hyperparathyroidism (high calcium, high PTH)
What cardiovascular changes are seen in the mother
increased CO (due to demand of fetal circulation)
increased HR
BP drops during 2nd trimester
why does BP drop during 2nd trimester
expanding uteroplacental circulation- decreased peripheral resistance
haematological changes seen in pregnancy
increased plasma volume
erythropoiesis (increased in RBC)
increased iron requirement
respiratory changes in pregnancy
increased O2 consumption to meet metabolic demands of fetus
role of progesterone in resp changes
signals brain to lower CO2 levels
achieved by:
increased RR
Increased tidal volume
renal changes seen in pregnancy
increased GFR + plasma flow
how do postural changes affect renal function
upright- decreased
supine- increased
lateral position during sleep- increased
what is pre-eclampsia
pregnancy induced hypertension + proteinuria
what leads to proteinuria
kidney function declines- salt + water retention
oedema
decreased renal blood flow + GFR
biggest risk for pre-eclampsia
previous pre-eclampsia
what is given from 12 weeks if high risk for pre-eclampsia
75mg aspirin daily
symptoms of eclampsia
LETHAL
vascular spasms, extreme hypertension, seizures, coma
treatment of eclampsia
vasodilators + C section
average maternal weight gain
24 lbs
how many extra calories does a woman need
250-300
what is given before labour to prevent intra-cranial bleeding
vitamin K
role of progesterone + oestrogen in labour
progesterone inhibits contractility, oestrogen increases contractility
where is oxytocin made
posterior pituitary
role of oxytocin
increases contractions
what does cervical stretching cause
further oxytocin release
effect of oxytocin on the placenta
stimulates it to make prostaglandins
this stimulates more vigorous contractions of the uterus
what stimulates milk production
prolactin
what inhibits milk production
oestrogen
progesterone
role of oxytocin in breast feeding
causes muscle contraction- smooth ejaculation of milk
