The placenta Flashcards
what cells develop into the placenta
trophoblast
what cells develop into the foetus
inner cell mass
the chorion ( trophoblast) splits into the 2 layers
synctiotrophoblast - outer layer - barrier and hormone secretion
cytotrophoblast
- inner layer contains prolific enzyme secretion - angiogenesis
where is the placenta implanted
endometrium
what artery supplies uterus
uterine artery - branch of internal iliac off aorta
spiral arteries supply what
endometrium
what artery which is a branch of ovarian supplies myometrium
arcuate artery
what is special about the placenta villi
high surface area for gas exchange and layer of synctiotrophoblast covering fetal vessels
do uterine contractions compromise flow
yes
450ml/min
fetal flow
500-600ml/min
maternal flow - 10% CO
what does the umbilical cord consists of
carries fatal blood
2 arteries deoxygenated to placenta
1 vein oxygenated from the placenta
what artery supplies umbilical
iliac artery
what is the amnion
membrane over embryo - fills with amniotic fluid and become protective envrionemtn for embryo
what is the chorion
double layer membrane formed by trophoblast cells gives rise to fatal part of placenta
how many cotyledons does a placenta have
15-25
what two techniques are used to look at placenta and embryo
Ultrasounds shows placental localization
Doppler shows umbilical cord insertion - flow
Shows health of umbilical flow
what hormone support pregnancy in first trimester r
HCG
what hormone is co-dependet in fatal adrenal function
oestrogen
what hormone does ,,Anti-insulin action makes more glucose available for foetus
human placental lactose
5 placental transfer mechanisms
passive diffusion - stérions facilitated diffusion - glucose active transport - aa and calcium endo/pinocytosis - immunoglobulisn osmosis - water
fetus has higher O2 affinity of HbF how does a small left shift of fatal graph encourage what
O2 uptake
delicate immunological truce prevents rejection of foetus what mechanisms
Placental secretion of phosphocholine (immune cloak)
Trophoblast has reduced antigenic (HLA) expression
Suppression of maternal cytotoxic T cell activity
Placental barrier to maternal lymphocytes
what is antigen D
rhesus positive
need to give 72 hours post part
ABO antibodies are IgM so do not cross the placenta
RH D antibodies are IgG - small
can they cross placenta
yes
placenta praaevia
symptoms
Placenta lying partly or entirely over the cervical opening ( cervical OS)
• Usually painless
• Visible bleeding usually matches level of
shock
painless bleeding
Can be different grades deepening on extent
of covering of the internal os
I - placenta reaches lower segment but not the internal os
II - placenta reaches internal os but doesn’t cover it
III - placenta covers the internal os before dilation but not
when dilated
IV - placenta completely covers the internal os
Placental abruption symptoms
Separation of the placenta from the uterine wall,
resulting in bleeding behind the placenta ( can be concealed - behind placenta or concealed track down to cervix)
• Normally very painful
• Shocked but may not have visible expected blood loss
• Life threatening to the foetus
What is a cord prolapse
what can the fetal head do
cord bulges through the cervix when membrane ruptures
fatal head compresses cord during contraction cutting off umbilical flow
pre-eclampsia
and symtoms for maternal
Hypertensive disorder of pregnancy
due to poor placental perfusion
placental vessels fail to develop so perfusion inadequate interpreted as shock from blood loss causing vasoconstriction so
- Hypertension and proteinuria- main symptoms
- May also present with:
- Frontal/occipital headache
- Visual disturbances
- Epigastric pain
- Oedema
- Hyper-reflexia
in foetus - growth retardation
What is seen in the classic triad of ectopic pregnancy?
• Implantation of the embryo not in the
uterine wall
• Not all women will present with all
three features
vaginal bleeding
amenorrhea ( absence of menstruation - missed periods 3 in a row)
acute abdominal pain
what is not seen in the classic triad of ectopic pregnancy
oligomenorrhea - infrequent menstrual periods
A 30 y/o, 26
-week
pregnant lady presents to the GP reporting she has had a headache and upper abdominal pain for the past 24 hours. The GP takes her blood pressure which reads 160/120mmHg. She decides to take a urine dipstick which shows +++ for protein. What is the most likely diagnosis?
pre eclampsia
A 34-week pregnant lady presents with a small amount of vaginal
bleeding and lower abdominal pain. Her blood pressure is 85/62 and
pulse is 118. What is the most likely diagnosis?
placental abruption
A 35-week pregnant lady presents with painless bleeding from the
vagina. Her pulse and blood pressure are normal. What is the most
likely diagnosis?
placenta praevia
