Absorption of materialsAbsorption of materials

Oxygen and nutrients from food must be absorbed into the bloodstream to be delivered to cells for respiration.

Waste materials such as carbon dioxide must be removed from cells into the bloodstream.

Tissues contain capillary networks to allow these exchanges to occur at a cellular level.

The surfaces involved in the absorption of materials have certain features in common:

• a large surface area
• thin walls
• extensive blood supply

These features increase the efficiency of absorption.