Placenta at term

Question 1

Functions of placenta

Answer 1

Protection 
Immunological
Nutrition
Respiration
Excretion
Endrocrine
Transportation

Question 2

Umbilical Cord

Answer 2

• inserted into centre of fetal surface
• 1-2cm diameter. 30-90cm length
• contains 2 arteries and 1 vein surrounded by Wharton’s Jelly
• oxygenated blood flows to baby via umbilical vein and deoxygenated blood returns to placenta via arteries

Question 3

The Membranes

Answer 3

• chorion is thick, opaque and friable and is continuous with edge of the placenta
• adheres to decide and amnion glides over it aided by mucous
• amnion strong and tough, smooth and translucent.
• covers fetal side of placenta and umbilical cord

BOTH produce prostaglandins, help to initiate labour

Question 4

Mature Placenta

Answer 4

Maternal = attached to decidua. at delivery dark red as contains mat blood. divided into 20 cotyledons separated by sulci

Fetal = covered in amnion, also covered umbilical cord - cord inserts centrally into the fetal surface. fetal blood vessels radiate out from cord, looks grey/white and shiny from amnion. amnion can be peeled off surface back to cord

Question 5

Amniotic Fluid

Answer 5

• clear, alkaline fluid derived from maternal circulation across placental membranes and from the fetus via urine and lung fluid
• allows for growth and movement of fetus =maintaining temp and equalising pressure
• comprises 9% water, remaining 1% is waste, skin cells, lanugo and vernix

Question 6

Placental Circulation

Answer 6

• fetal blood low in 02 is pumped by fetal heart towards placenta along umbilical arteries and transported along their branches to capillaries of villi
• 02 passes from mat blood into fetal blood and is returned to fetus via umbilical vein
• mat blood is delivered to placental bed by spiral arteries and flows into spaces surrounding villi