- Inner surface of ileum is folded extensively - and has numerous minute finger like projections called villi (singular villus) → to increase SA to V ratio of food to cells for absorption
- epithelium or walls of villus is only one cell thick - to provide a short diffusion distance for nutrients to pass through → faster ROD
- Cells of the epithelium → have many microvilli to further increase SA to V ratio of food to small intestine.
- Each villus also has many blood capillaries that allow blood to transport absorbed glucose and amino acids in order to maintain a steep diffusion gradient.
- each villus contains a lacteal to transport absorbed fats away and maintain a steep diffusion gradient.
- epithelial cells contain many mitochondria to provide energy (through aerobic respiration) for active transport of nutrients into the villi.