physiology of pregnancy and lactation Flashcards
fertilised egg develops and differentiates into a
blastocyte
transport into uterus on day ?
3-5
attaches to lining ofuterus on day?
5-8
blastocyst - inner cells develop into embryo, outer cells burrow into uterine wall and become placenta. what does the placenta produce which maintains pregnancy>
hormones
blastocyst lined by?
trophobalst cells
when blastocyst adheres to the endometrial lining, chords of trophoblastic cells….?
begin to penetrate into the endometrium
advancing chords of trophoblastic cells tunnel deeper into the endometrium, carving a hole for the blastocytes
when implantation is finished, blastocyst is completely buried in endometrium
completely delved by?
day 12
placenta is derived from both …cells and …cells
trophoblastic and decidua
trophoblast cells differentiate into multinucleate cells, (syncytiotrophoblasts), which invade decidua and break down capillaries to form cavities filled with maternal blood
y
what does the developing embryo do?
sends capillaries into the syncytiotrophoblastic projections to form placental villi
placental villi - separate maternal blood and fetal blood by thin layer of tissue. is there exchange?
no
when is the placenta functional by?
5th week of pregnancy
early nutrition of the embryo?
invasion of the trophoblastic cells into the decieua
hcg signals the corpus luteum to continue secreting?
progesterone
progesterone stimulates the endometrium to concentrate which substances?
glycogen, protens and lipid
as placenta develops, it extends hair like projections into the uterine wall
this increases contact area between the uterus and placenta
a thin membrane separates fetal blood from maternal blood. what is the space called between this>
intervillous space
the placenta plays the role of?
fetal lungs
exchange takes place between maternal (oxygen rich blood) and umbilical cord (arterial and venous blood)
y
oxygen rich blood travels to the fetus via the?
umbilical vein
maternal oxygen poor blood travels back into the ?
uterine veins
deoxygenated blood from fetus..pathway?
umbilical arterIES - (maternal) uterine vein
3 factors which facilitate oxygen supply to the fetus?
fetal haemoglobin has an increased ability to carry 02, have more haemoglobin, 3 = bohr effect (fetal hb can carry more oxygen in low PC02)
how does water diffuse across placenta?
osmosis, exchange increases during pregnancy up to 35th week. (3.5l/day)
how do electrolytes get across?
follow water
which electrolytes only go from mother to child?
iron and ca
how does glucose cross the placenta?
simplified transport (scsp)
free diffusion of?
fatty acids
there is an increased demand of glucose for the fetus in?
3rd trimester
what effect does HCG have on male testes?
development of sex organs
HCS - what week of pregnancy does it start being produced?
week 5
it has growth hormone like effects, what tissue does it act on?
protein
how does it get more glucose for the fetus?
decreases insulin sensitivity in the mother
what is it also involved in the development of?
breast development
progesterone - when does is start to rapidly increase?
week 10. 10 deci. prep.
what is it involved in?
development of decidual cells, preparation for lactation, decreases uterine contractility
effect of estradiol on uterus?
increased proliferation
what hormone is involved in the relaxation of ligaments?
oestrogen (east)
which hormone acts like thyroid hormones
HCG
mimics hyperthyroidism
y
increased calcium demands in pregnancy can lead to?
hyperparathyroidism
cardiac output in pregnancy?
30 - 50% higher(beginning in week 6, peaking week 24)
when does it decrease?
in the last 8 weeks
what happens to the heart rate?
increases to 90 per minute to increase cardiac output
when does blood pressure drop?
2nd semester
specifically with twins, what happens to blood pressure and cardiac output?
blood pressure drops more, CO increases more
what happens to plasma volume>
increases proportiaonally with co
what happens to hb as a consequence?
concentration is reduced, and blood viscosity decreases
in the second half of pregnancy, there is a significant increased requirement for what? what supplements are needed>
iron
wjy are there respiratory changes?
partly due to increased progesterone, partly due to pressure of uterus interfering with lung function
what does progesterone signal?
brain to lower CO2 levels
because of these signals to lower co2 levels, what happens to resp rate/tidal volume, pc02, vital capacity and P02
all decrease, except P02 and vital capacity remain the same
what happens to GFR and plasma renal flow?
increases by 30-50%
why is there increased reabsorption of ions and water?
placental steroids
urine formation?
slight increase
how do postural changes affect renal function?
upright position decreases it, supine position increases it, lateral position during sleep increases it more
pregnancy induced hypertension and proteinuria?
pre eclampsia
when is the cut off for gestational hypertension?
20 weeks, must be after 20 weeks
if woman has hypertension before 20th week, what is diagnosis?
pre existing hypertension
pre eclampsia more common in women with pre existing hypertension, diabetes, autoimmune diseases, family history, avesity and women with multiple gestation
y
what is the single biggest risk factor?
previous pre eclampsia
what is eclampsia>
extreme pre ecampsia
vascular spasms, extreme hypertension, chronic seizures and coma
y
treatment of eclampsia?
vasodilators and caesarean section
average weight gain ?
24lbs
250-300 extra k/cal/day
extra protein intake 30g per day
what is the fetal glucose need at the end of pregnancy?
`5mg/kg/min
glucose need of the mother
2.5mg/kg/min
when is mothers anabolic phase?
1st - 20th week
during anabolic phase for mother, anabolic metabolism for mother, and quite small catabolic needs for the baby
weeks 21–40 - high metabolic demands of the fetus, accelerated starvation of the mother
in the anabolic phase, mothers build ?
fat and glycogen
in anabolic phase what is insulin sensitivity like?
normal/increased
thererefore, what is the plasmatic glucose level like?
low
what happens to glycogen stores?
increased (building glycogen)
what happens re fat?
lipogenesis
basically in anabolic phase, you build glycogen and fat
y
in catabolic phase, you get insulin resistance, what hormones cause this>
HCS, cortisol and growth hormone
what are some special nutritional needs in pregnancy?
high protein diet, iron supplements, b vitamins, folic acid
what are b vitamins for?
erythropoesis
whats folic acid for
reduce risk of neural defects
what should be given, before partuition, to reduce the risk of intercranial bleed during labour?
vitamin K
progesterone decreases uterine contractibility
ratio of e:p changes at partiution
what hormone (from pp gland) increases contraction and contractibility
oxytocin
what does mechanical stretch of the uterine muscles cause?
increased contractibility
stretch of _____also stimulates uterine contractions
cervix
what happens to the frequency of Braxton hicks contractions?
increase towards end of pregnancy
stretch of the cervix by fetal head increases contractility, this is an example of?
positive feedback
cervical stretching also causes further release of?
oxytocin
strong uterine contractions and pain from the birth canal cause neurogenic reflexes from spinal cord that iduce intense abdominal contractions
u
what does oestrogen do to the uterus which stimulates uterus to contract and placenta to make prostaglandins>
induces oxytocin receptors
what do prostaglandins do?
stimulate more vigorous contractions of the uterus
