08. Role of placenta and amniotic fluid

What are its roles?

Exchange of gases and nutrients, barrier between maternal and foetal blood, secretion of hormones

What is exchanged in the placenta specifically?

Nutrients, waste products, oxygen and carbon dioxide

Why does there need to be a barrier between maternal and foetal blood?

There’s higher blood pressure in mother than foetal capillaries

How is there a barrier between maternal and foetal blood?

Cells of chorionic villi fuse together, preventing mother’s phagocytes from passing onto foetus, whilst mother’s antibodies are small enough to cross into foetal blood and provide it with passive immunity

What does the placenta act as?

An endocrine gland

What does amniotic fluid do?

Act as shock absorber, preventing injury to foetus

What are some features placenta?

Chorionic villi, umbilical arteries and veins, intervillious space

Why are chorionic villi adapted?

For efficient exchange

How are chorionic villi adapted?

Microvilli to increase SA, thin walls for short diffusion distance, counter current flow to maintain concentration gradient

What does the umbilical veins and arteries do?

Transports materials between mother and foetus

What does the intervillious space do?

Contain mother’s blood around chorionic villli, preventing the mixing of blood