Humans require transport systems to supply their cells and remove waste products. Gas exchange occurs in the lungs and food molecules are absorbed by the digestive system.
Part of BiologyMulticellular organisms
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:
These features increase the efficiency of absorption.