placenta

Question 1

spiral artery remodelling

Answer 1

A subset of cytotrophoblast cells differentiate to become extravillous trophoblast cells

Invade into the maternal endometrium, myometrium then spiral arteries

These cells remodel the coiled vessels from low flow, high resistance to become wider, high flow, low resistance channels

Allows sufficient blood flow to the fetus

Question 2

in early pregnancy

Answer 2

In early pregnancy the embryo receives nutrients from uterine glands, before the chorionic villi / intervillous space is developed

Question 3

gross anatomy of placenta

Answer 3

At term, the gross placenta has a chorionic (fetal-facing) and basal (maternal-facing) plate, and is connected by the umbilical cord which contains 2x umbilical arteries, and 1 umbilical vein

Question 4

placental nutrient transport, maternal blood

Answer 4

Maternal blood (rich in oxygen and nutrients) flows from the uterine arteries into large blood sinuses surrounding the villi, then back into the uterine veins

Question 5

placental nutrient transport, fetal blood

Answer 5

Fetal blood, (low in oxygen and nutrients), flows through umbilical arteries to capillaries of the villi & returns through umbilical vein to the fetus

Question 6

placental nutrient transport steps

Answer 6

1. diffusion
2. paracellular diffusion
3. transporter-mediated transfer
4. endocytosis-exocytosis