Placental Villi: Enhancing Nutrient Exchange & Waste Removal

Microscopic villi on the placental surface dramatically increase diffusion rate between maternal and fetal circulations.

How Villi Facilitate Diffusion

1. Increased Surface Area: More contact between maternal blood and fetal capillaries.
2. Thin Epithelial Barrier: Short diffusion distance for nutrients, gases, waste.
3. Capillary Network: Fetal capillaries surround maternal vessels for efficient exchange.
4. Concentration Gradients: Maternal nutrient supply and fetal waste removal maintain gradients driving diffusion.
5. Active Transport: Energy-dependent movement of essential nutrients against gradients.
6. Blood Flow: Continuous maternal flow over villi and fetal flow through capillaries sustains gradients; uterine contractions enhance flow.

These features create an optimal environment for rapid nutrient/oxygen delivery and waste removal, supporting fetal growth.