Placental and foetal physiology

Question 1

What are the potential foetal complications in pregnancy that can occur as a result of elevated levels of oxidative stress?

Answer 1

Villous regression, formation of smooth chorion leavae

Question 2

What is a histiotroph?

Answer 2

nutritional material in space between the maternal and foetal tissues, derived from the maternal endometrium and uterine glands

Question 3

How are spiral arteries in the placenta plugged?

Answer 3

During early pregnancy the volume of endovascular trophoblast is such that it plugs the mouths of the spiral arteries, preventing maternal blood flow into the placenta.

Question 4

What are the functions of the placenta?

Answer 4

Respiratory organ
Nutrient transfer
Excretion of foetal waste products
Hormone synthesis

Question 5

What proteins are present in the apical membrane of the placental syncytiotrophoblast which facilitate nutrient transport?

Answer 5

Fatty acid transporters, glucose transporters, amino acid transporters

Question 6

What are the different systems by which amino acids can be transported across the placenta?

Answer 6

System A: sodium dependent; transports small non-essential amino acids.
Exists in 3 isoforms (SNAT1 mainly, SNAT2, SNAT4)
Regulated by hormones (insulin, leptin)

System L: sodium independent; non essential amino acids exchanged for essential amino acids. Regulated by mTOR nutrient sensing pathway.

Taurine transporter: cotransport with Na and Cl, against concentration gradient.

Question 7

Describe system A for placental amino acid uptake

Answer 7

sodium dependent; transports small non-essential amino acids.
Exists in 3 isoforms (SNAT1 mainly, SNAT2, SNAT4)
Regulated by hormones (insulin, leptin)

Question 8

How is system A for placental amino acid uptake regulated?

Answer 8

Hormones (insulin, leptin)

Question 9

Describe system L for placental amino acid uptake

Answer 9

sodium independent; non essential amino acids exchanged for essential amino acids. Regulated by mTOR nutrient sensing pathway.

Question 10

How is system A for placental amino acid uptake regulated?

Answer 10

Regulated by mTOR nutrient sensing pathway.

Question 11

How are fatty acids transported across the placenta?

Answer 11

Lipoprotein lipase releases non-esterified fatty acids from triglycerides in lipoproteins.

They are then transported across the trophoblast cells by fatty acids transport proteins.