physiology of pregnancy Flashcards
what tissue is the placenta derived from
trophoblast and decidual tissue
at what stage of pregnancy is the placenta and foetal heart functional
5th weeks of pregnancy
what provides nutrition to the embryo in the early stages of pregnancy
invasion of trophoblastic cells into the decidua
what effect does HCG have on the corpus luteum in early pregnancy
signals it to continue secreting progesterone
progesterone stimulates decidual cells to concentrate glycogen, proteins and lipids
how does the placenta maximise contact area with maternal circulation
extends hair-like projections (villi) into the uterine wall
what sort of blood is contained in the umbilical circulation
mixed arterial and venous blood
oxygen-poor
foetal, oxygen saturated blood returns to the fetus via …..
the umbilical vein
maternal, oxygen-poor blood flows back into the …..
uterine veins
supply of the fetus with oxygen is facilitated by which three factors
fetal Hb (increased ability to carry O2) higher Hb concentration in fatal blood Bohr effect (fetal Hb can carry more O2 in low pCO2 than in high pCO2)
effect of HCG
prevent involution of corpus luteum
effect on the testes of male fetus (development of sex organs)
effects of HCS
produced week 5 of pregnancy
growth hormone-like effects (protein tissue formation)
decreases insulin sensitivity in mother (more glucose for fetus)
involved in breast development
effects of progesterone
development of decidual cells
decreases uterus contractility
preparation for lactation
effects of estrogens
enlargement of uterus
breast development
relaxation of ligaments
why does CO increase during pregnancy
due to demands of the uteroplacental circulation
during which trimester does BP drop
2nd trimester
why might a pregnant person become faint when lying supine towards the end of the pregnancy
the uterus compresses the vena cava
physiological changes to lower CO2 levels
respiratory rate increases tidal and minute volume increases pCO2 decreases slightly vital capacity and pO2 don't change (progesterone)
physiological changes in urinary system
glomerular filtration rate and renal plasma flow increases
increased reabsorption of ions and water
slight increase in urine formation
how do postural changes affect renal functions
upright position = decrease
supine position = increase
lateral position during sleep = increaseee
what is pre-eclampsia
pregnancy induced hypertension and proteinuria
signs of pre-eclampsia
increasing BP since 20th weeks
oedema in hands and face
what is the single most significant risk for pre-eclampsia
having had pre-eclampsia before
what causes pre-eclampsia
insufficient blood supply to placenta
what are signs of eclampsia
vascular spasms
extreme HTN
chronic seizures
coma
treatment of eclampsia
vasodilator
c-section
what is the average weight gain during pregnancy
24 lbs
what are the components that make up the weight gain during pregnancy
fetus extra-embryonic fluid/tissues uterus breasts body fluid fat accumulation
how many extra calories should be consumed by the mother
250-300 calories a day
what are the 2 phases of pregnancy (regarding maternal-fetal metabolism)
1st-20th week = mother’s anabolic phase
21st-40th weeks = mother’s catabolic phase
what happens with the mother’s anabolic phase
normal or increased sensitivity to insulin
lower plasmatic glucose level
lipogenesis, glycogen stores increase
growth of breasts, uterus, weight gain
what happens during catabolic phase
maternal insulin resistance
increased transport of nutrients through placental membrane
lipolysis
special nutritional needs in pregnancy
folic acid vit D high protein diet iron supplements b vitamins
effect of oestrogen:pregesterone ratio on uterus excitability
progesterone inhibits contractility
oestrogen increases contractility
where is oxytocin produced
maternal posterior pituitary
what is the function of oxytocin during parturition
increases contractions and excitability
which fetal hormones are involved in parturition
oxytocin
adrenal gland
prostaglandin
mechanical factors tan increase contractility
mechanical stretch of uterus
stretch of cervix
what kind of feedback is involved in the onset of labour
positive feedback
stretch of the cervix by fetal head increases contractions
which hormone is released in response to cervical stretch in the initiation of labour
oxytocin
which hormones are released in response to oxytocin release
prostaglandins
what is the first stage of labour
cervical dilation (8-24 hours)
what is the second stage of labour
passage through birth canal (few minutes to 120 minutes)
3rd stage of labour
expulsion of placenta
what hormones are involved in producing and releasing milk
oestrogen: growth of ductile system
progesterone: development of lobule-alveolar system
prolactin: stimulate milk production
which hormones inhibit milk production during pregnancy
oestrogen and progesterone
what are the 5 steps of the milk let-down reflex
1 - receptors in nipple stimulated 2 - impulses propagated to spinal cord 3 - stimulation of hypothalamic nuclei 4 - oxytocin released 5 - milk ejected
