Physiology of Pregnancy and Puerpium Lactation Flashcards
the fertilised ovum divides and differentiates into what structure?
a blastocyst
what is the name of the egg from its journey from the site of fertilisation to the endometrium?
blastocyst
how many days does it take for the blastocyst to ENTER the uterus?
3-5 days
how many days does it take for the blastocyst to IMPLANT in the uterus?
5-8 days
what do the inner cells of a blastocyst form?
embryo
what do the outer cells of a blastocyst form?
placenta
name the cells of the blastocyst that invade the endometrial cavity
trophoblast cells (surface layer of the blastocyst)
what signifies the end of implantation?
when the blastocyst is completely buried in the endometrium
how many days after fertilisation is the end of implantation?
day 12
the placenta is derived from what 2 types of tissue?
trophoblast
decidual tissue
another word for trophoblast cells?
chorion
how are placental blood vessels formed?
- trophoblast cells invade decidua and breaks down capillaries to form cavities for maternal blood
- embryo creates blood vessels which insert into the cavities to form villi
N.B foetal capillaries and maternal blood are separated by a thin layer to prevent cross contamination
in what week of pregnancy are the placenta and foetal heart functional?
week 5
what does HCG do?
signals the corpus luteum to continue secreting progesterone
what effect does progesterone have on decidual cells?
stimulates them to concentrate glycogen, protein and lipids
why does the placenta contain villi?
increases contact area between uterus and placenta
allows more nutrients and waste to be exchanged
the thin membrane separating mums blood from babys in the placenta is located in what space?
intervillous space
what makes up umbilical blood? how oxygenated is it?
mix of arterial and venous blood
poorly oxygenated
how oxygenated is mums blood in the placenta?
oxygen rich
describe the transport of oxygen within the placenta?
O2 diffuses from M to B’s circulation
CO2 diffuses from B to M’s circulation
what vessel transports oxygen rich blood to the foetus?
umbilical vein (because it’s LEAVING the placenta)
what vessel transports maternal oxygen poor blood?
uterine veins
what 3 factors facilitate oxygen transport to the foetus?
foetal Hb
higher Hb concentration in fetal blood
Bohr effect
what is the bohr effect?
fetal Hb can carry more oxygen in low pCO2 than high pCO2
PO2 is higher in mum/baby
PCO2 is higher in mum/baby
mum
baby
a fetus has a __% higher Hb concentration than an adult; why is this?
50
to give them an increased ability to carry O2
what 2 electrolytes can only go from mother to child?
iron
Ca
what substance is the fetus’ main source of energy?
glucose
exchange of water increases during pregnancy T or F
T
what substances diffuse freely across the placenta?
fatty acids
glucose crosses the placenta via what process?
simplified transport
HCG peaks at how many weeks gestation?
10
human chorionic somatomammotropin is produced from around week _ of pregnancy
5
what does HCS do?
GH-like effects eg on protein tissue
decreases insulin sensitivity
breast development
why are pregnant women more insulin resistant?
to provide more glucose for the foetus
what does progesterone do?
develops decidual cells
decreases uterine contractility
preps for lactation
what does oestrogen do?
enlarges uterus
breast development
relaxes ligaments
what pituitary hormone is also synthesised by the placenta? what does it stimulate release of?
CRH
ACTH
effect of increased CRH in pregnancy?
excess cortisol can cause insulin resistance -> GDM
excess aldosterone can cause HT
main consequence of excess HCG production? why is this?
hyperthyroid
can mimic TSH
what effect can pregnancy have on the parathyroid gland and why?
hyperparathyroidism
increased Ca demands
cardiac output increases/decreases in pregnancy, why is this?
increases
increased demands from the uteroplacental/renal circulation and inc metabolism
CO increases by __%
30-50
at what gestation does CO peak?
24
its normal to have ECG changes and heart sounds in pregnancy T or F
T
a HR of up to _ BPM is normal in pregnancy
90
when does BP drop in pregnancy and why?
2nd trimester
uteroplacental circulation expands and TPR decreases
when pregnant with twins CO ___ and BP ____ more
increases
decreases
___ increases proportionally with CO
PV
how much iron is needed in the second half of pregnancy per day?
6-7mg a day
what effect does progesterone have on the lungs?
instructs the brain to lower CO2 levels to increase O2 consumption (needed by fetus, placenta and mother)
GFR decreases in pregnancy T or F
F, increases as does renal plasma flow
what happens to reabsorption of ions in the kidneys in pregnancy?
increases
3 main features of pre-eclampsia?
pregnancy induced hypertension
proteinuria
oedema
what happens to the kidneys in pre-eclampsia?
renal blood flow and GFR decrease
get salt and water retention = oedema
biggest risk for pre-eclampsia?
previous pre-eclampsia
presentation of eclampsia?
SEVERE
vascular spasms, extreme hypertension, chronic seizures, coma
Tx of eclampsia?
vasodilators
CS
average weight gain of the mother in lbs
24lbs
how much extra protein should be ingested by mum?
30g per day
at what trimester is mum’s metabolism at its most anabolic? why is this?
1st and some of 2nd
need to store energy and glucose for the foetus
growing breasts/uterus/weight
at what trimester is the mother most insulin resistant?
3rd trimester
what effect does progesterone have on uterine contractility?
inhibits it
what produces oxytocin?
POSTERIOR pituitary gland
what does oxytocin do?
increases uterine excitability by:
- stimulating uterus to contract
- stimulating placenta to make prostaglandins (stimulates more contractions)
describe the positive feedback mechanism of labour?
stretching of structures eg the cervix by the fetal head:
increases contractility by increasing oxytocin release
increases abdo contractions caused by reaction to pain
what hormone stimulates oxytocin receptors on the uterus?
oestrogen
name the 1st stage of labour and how long it lasts
cervical dilatation
8-24hrs
name the 2nd stage of labour and how long it lasts
passage through birth canal
few mins to 2 hours
name the 3rd stage of labour
expulsion of the placenta
describe the role of oestrogen in lactation?
growth of the ductile system
what hormone develops the lobule alveolar system
progesterone
oestrogen and progesterone inhibit/promote milk production
inhibit
there is a drop after birth which increases lactation
what 2 hormones need to be increased for milk to be produced?
oxytocin
prolactin
steroids are given to premature babies
30
protects the brain
