Physio in pregnancy* Flashcards
what happens to the fertilised ovum first and what does it form
when does this happen
divides and differentiates into a blastocysts
as it moves from the site of fertilisation in the upper oviduct to the site of implantation in the uterus
what happens at day 1
fertilisation occurs in the ampulla of the fallopian tube
what happens during days 3-5
transport of blastocyst into the uterus
what happens during days 5-8
what happens to the blastocyte
what happens to the placenta
blastocysts attached to the lining of the uterus
inner cells form embryo and outer cells burrow into uterine wall and become placenta
produces hormones to maintain pregnancy
how is the blastocysts implanted into the uterus
free floating blastocyst attaches to the endometrial lining
cords of the trophoblastic cells begin to penetrate the endometrium and tunnel deeper carving a hole for the blastocyst
boundaries between cells int eh advancing trophoblastic tissue disintegrate
what day is the blastocyst completely buried in the uterine lining
by day 12
what is the placenta derived from
trophoblastic cells (chorion) and decidual tissue
what happens to the trophoblastic cells
they differentiate into multinucleate cells called syncytiotrophoblasts which invade the decide and break down capillaries to form cavities form maternal blood
what does the developing embryo send into the synctiotrophoblast projections
capillaries
placental villi
what does each villus contain
what does this so
foetal capillaries separated from maternal blood by a thin layer of tissue in the intervillous space
2 way exchange of rep gases, nutrients, metabolites between mother and foetus down a diffusion gradient
when is the placenta and foetal heart functional by
the 5th week of pregnancy
how is the placenta developed
HCG singles the CL to continue secreting prog which stimulates the decidual cells to concentrate glycogen, proteins and lipids
what does the placenta work as
a physiological arteriovenous shunt
what happens as the placenta develops and why
it extends hair like projections (villi) into uterine wall
this increases contact area between the uterus and the placenta and more nutrients and waste materials can be exchanged
blood vessels from the embryo develop where
in the villi
cicrculation within the intervillous space acts as what
partly as a arteriovenous shunt
what role does the placenta play
what does the exchange take place between
fetal lungs
maternal oxygen rich blood and the umbilical blood
what does fatal oxygen saturated blood return to the fetus in and what does the maternal oxygen poor blood flow back in
umbilical vein
uterine veins
supply of the fetus with oxygen facilitated by what
fetal Hb - increased ability to carry oxygen
higher Hb - concentration in fatal blood - 50% more than adults
Bohr effect - fatal Hb can carry more oxygen in low CO2 than in high CO2
what membrane transport mechanisms lead to placental exchange processes
passive transport simple diffusion osmosis simplified transport active transport
how does water diffuse into the placenta
does the exchange increase
by osmotic gradient
increases during pregnancy up tot he 35th week - 3.5l/day
electrolytes follow what
and what two things can only go form mother to child
follow water
iron and calcium
how is glucose passed to the child
when is high glucose needed
passes placenta via simplified transport
3rd trimester
fatty acids reach the child how
free diffusion
waste products leave the fetus how
concentration gradient
what drugs can cross placental barrier
thalidomide, carbamazepine, coumarins, tetracycline
alcohol, nicotine, heroin, cocaine, caffeine
What does HCG do
prevent involution of the CL
effect on the tests of the male fetus - development of the sex organs
what does HCS - produced?
what does it do
produced from week 5 of pregnancy
growth hormone like effects - protein tissue formation
decreases insulin sensitivity in mother - more glucose for the fetus
involved in breast development
what does progesterone do
development of decidual cells
decreases uterus contractility
prepares for lactation
what does oestrogen’s do
enlargement of uterus
breast development
relaxation of ligaments
estriol level - indicator of vitality of fetus
what changes in CO during pregnancy
it increases due to demand of the uteroplacental circulation
how much does the CO increase and when
when does it peak
what does it lead to
30-50% above normal - begins week 6 and peaks at week 24
placental circulation, increased metabolism, thermoregulation, renal circulation
when does the CO decrease and what happens during labour
in the last 8 weeks - become sensitive to body position - uterus compresses vena cava
increases 30% during labour
what happens to the heart rate during preg
increases up to 90bpm to increase CO
what happens to blood pressure during preg
drops during the 2nd trim as uteroplacantal circulation expands and peripheral resistance decreases
what happens to cardiovascular changes during in pregnancy with twins
CO increases more and BP drops more
what haematological changes occur during pregnancy and why
plasma volume increases proportional to CO (50%)
RBC increases -25%
Hb is decreased by dilution - decreases blood viscosity
iron requirements increase 6-7mg/day in 2nd half of preg
iron supplement needed
respiratory changes during preg
why
what
progesterone signals brain to lower Co2 levels
O2 consumption increases (20% above normal)
growing uterus interferes with lung action
SO
resp rate increases
tida and minute volume increases by 50%
pco2 decreases slightly
vital capacity and pO2 don’t change
changes in the urinary system during pregnancy
glomerular filtration rate and renal plasma flow increase up to 30-50% and oaks at 16-24 weeks
increased re absorption of ions and water
- placental steroids, aldosterone
slight increase of urine formation
postural changes affect renal functions
upright position decreases
supine position increases
lateral positions during sleep increases
what is pre eclampsia
pregnancy induced hypertension and proteinuria
what are the signs of pre eclampsia
increasing BP since the 20th week
kidney function declines - salt and water retention - oedema formation esp in hands and face
RBF and GFR decreases
who is pre eclampsia more common in
single most significant risk is what
pre existing ht, DM, autoimmune disease, renal disease, FH, obesity, multiple gestation
had pre eclampsia previously
what causes pre eclampsia
extensive secretion of placental hormones
immune response to fetus
insufficient blood supply to placenta
what is eclampsia
symptoms
treatment
extreme pre eclampsia
vascular spasms, extreme hypertension, chronic seizures and coma
vasodilators and C sec
maternal average weight gain total
fetus fluid/tissue uterus breasts body fluid fat accumulation
24
7 4 2 2 6 3
how much extra calories have to be taken in by the mother during pregnancy and what happens to it
250-300 kcal/day
85% fetal metabolism and 15% stored as maternal fat
how much extra protein intake does the mother have to take
how much glucose does the fetus need
30g/day
by the end of the pregnancy 5mg/kg/min
what are the two phases of the pregnancy in relation to maternal-feral metabolism
1-20 weeks mother anabolic phase
anabolic metabolism of the mother
small nutritional demands of the conceptus
21-40 weeks esp in the last trimester - catabolic phase
hig metabolic demands of the fetus
accelerated starvation of the mother
what is the anabolic phase
normal of increases sensitivity to insulin
lower plasmatic glucose level
lipogenesis, glycogen stored increases
growth of breasts, uterus, weight gain
what is the catabolic phase
accelerated starvation
maternal insulin resistance
increases transport of nutrients through the placental membrane
lipolysis
why is insulin resistant caused by and which phase is it in
HCS, cortisol and GH
catabolic phase
what is the special nutritional need in pregnancy
higher protein and energy intake
iron supplenments - 300mg ferrous sulfate
B vitamine - erythopoesis
Folic acid
Vit D3 and calcium suppléments
K vitamins before parturition to prevent intracranial bleeding during labour
why is folic acid given
reduces risk of neural tube defects
what happens to the uterus towards the end of the pregnancy and why
becomes more excitable
estrogen: prog ratio alters leading to excitedness
prog inhibits contractility and oestrogen increases it
what does oxytocin do at the time of birth
from mother pit gland
increases contractions and excitability
what are the fatal hormones and what do they do
oxytocin, adrenal gland, prostaglandin
control timing of labour
what part do muscles and the cervix play in birth
mechanical stretch of uterine muscles increase contractility
stretch of cervix also stimulate uterine contractions
what happens during the onset of labour
braxton hicks contractions
stretch of cervix by head increases contractility - pos feedback
cervical stretching - further oxytocin release
strong contraction and pain causes neurogenic reflexes from spinal cord that induce strong abdominal muscle contractions
1st stage of labour
2nd
3rd
cervical dilation (8-24 hours) passage through birth canal (few mins to 30) expulsion of placenta
what causes growth of ductile system
what causes development of lobule-alveolar system
what inhibits milk production and what happen to these at birth
estrogen
prog
E and P - drop in them
what stimulates milk production
prolactin - steady rise in week5-birth
1-7 days after birth 0 high levels of prolcatin
stimulates colostrum (low volume, no fat)
whats a stimulus for lactation and what does oxytocin do
suckling
milk let down reflex
