Adaptations of the Small Intestine (Cambridge (CIE) IGCSE Biology): Revision Note

Adaptations of the small intestine: Extended

Extended Tier Only

• The ileum is adapted for absorption as it is very long and has a highly folded surface with millions of villi (tiny, finger like projections)

• These adaptations massively increase the surface area (opens in a new tab) of the ileum, allowing absorption to take place faster and more efficiently

• Microvilli on the surface of the villus further increase surface area for faster absorption of nutrients

• Wall of the villus is one cell thick meaning that there is only a short distance for absorption to happen by diffusion and active transport

• Well supplied with a network of blood capillaries that transport glucose and amino acids away from the small intestine in the blood

• Lacteal runs through the centre of the villus to transport fatty acids and glycerol away from the small intestine in the lymph