The intestines are a long continuous tube – running from stomach to anus – where the absorption of nutrients and water occurs
- The intestines can be divided into the small intestines (nutrient absorption) and large intestines (water absorption)
Small Intestines
The small intestine is comprised of three distinct regions: duodenum, jejunum and ileum
Duodenum
- First segment of the small intestine which is fed by digestive fluids from the pancreas and gall bladder
- Bile emulsifies fat globules into smaller droplets and pancreatic juice contains digestive enzymes
- Sodium bicarbonate is released from the pancreas to neutralise stomach acids such that intestinal pH is ~ 7
Jejunum
- Second segment of the small intestine where the digestive process is largely completed
- Pancreatic enzymes and enzymes released from intestinal glands complete the break down of sugars, proteins and lipids
Ileum
- Final segment of the small intestine with the principal function of nutrient absorption
- The intestinal tract is highly folded (villi and microvilli) to increase surface area and optimise material absorption
- Bile is also absorbed here and returned to the liver via blood vessels
Large Intestine
The principal function of the large intestine is to absorb any remaining water and mineral ions
- The large intestine is divided into the ascending colon, transverse colon, descending colon, sigmoidal colon and rectum
- The appendix is also considered a part of the large intestine although it is a vestigial remnant without an important function
Sections of the Intestines
