Fetal and placental physiology Flashcards
What is cortisol essential for in fetal dev?
- lung compliance and surfactant production
- B R and glycogen deposition in the liver
- villus prolif and digestive enxymes
Where does oxygenation occur in the fetus?
The placenta
What structures allow the fetal lungs to be bypassed?
- ductus venosus - shunts blood away from liver
- ductus arteriosus - shunts blood from pulm trunk to aorta
- foramen ovale -blood from right to left atrium
DRAW FETAL CIRULATION OUT
What keeps to DA open and what closes it prem?
PGE2 and prostacyclin
COX
After birth what happens to fetal circ?
Drop in P - FO closes
Vent of lungs = decrease vasc resist
What does surfactant do?
fills fetal lungs with fluid - allows them to expand (find video)
What is oligohydramnios?
Not enough amniotic fluid - if there is not enough fluid in the lungs then they will not grow properly
Where is fetal blood produced?
Yolk sac - liver (5w) - bone (dom from 26w)
What is different about fetal blood?
Hb has 2a and 2b chains - higher affinity for oxygen
When does the switch from HbF to HbA occur?
28-34 wk
What happens if there is abnorm Hb?
Thalassaemia
When are lymphoctyes prod?
From 8w
What cells appear mid 2T?
Phago, T and B cells
Which Ig can cross placenta?
IgG
What general immunological defenses are in place?
Amniotic fluid (IgG)
Placenta (phgo)
Granuloctyes from liver and BM
Interferon from lymphocytes
When is the fetal skin similar to the adult?
23wk
What is the vernix?
Desequemated skin, cholesterol, glycogen
Prem babies don’t have it - H20 loss
What happens during gut form?
It herniates into umbilical cord as it grows faster than the abdomen
When does the gut reenter? What happens if it doesn’t?
12wk
In sac - omphalocele
Gastroschisis - not in sac
Swallowing reflex
Develops naturally
Failure = polyhydroamnios
When is nephrogenesis complete?
By 36wk - maturation is gradual
What forms most of the amniotic fluid?
Fetal urine - kindey failure = oligohydra
What is the increase in amniotic fluid?
30ml - 1000ml at term
What is the function of amniotic fluid?
Protect
Allow movement
Stop adhesions
Lung development
