Difference Between Small Intestine And Large Intestine

Small Intestine and the Large intestine are the tubular structures starting from the stomach to the anus. They differ in their functions. The small intestine helps in the digestion and absorption of food whereas the large intestine helps in the absorption of water and electrolytes.

Difference Between Small Intestine and Large Intestine

Small Intestine

• It is a 5 to 7m long tube that extends from the stomach to the large intestine.
• It extends from the pyloric sphincter to the ileocaecal valve.
• It is narrower and longer than the large intestine.
• It is divided into three parts-
  • Duodenum: It is a 0.25m long C-shaped curve and the first part of the small intestine. It is the smallest part of the small intestine. In sub mucosa of duodenum, Brunner's glands are present. The hepatic-pancreatic opening is also present in the duodenum.
  • Jejunum: It is 2.5m long and is the middle part of the small intestine.
  • Ileum: It is 3.25m long and is the last part of the small intestine. It is highly coiled. The ileocaecal valve is present between the ileum of the small intestine and the caecum of the large intestine. A secondary Lymphoid organ, known as Paeyer's patches which is a part of MALT is also present in the mucosa and submucosa of the ileum.

Structures present in the complete Small intestine

Microvilli, villi, and Plica circularis help in increasing surface area for the absorption of food. In villi, Lacteal (lymph capillary) is present that absorbs fat-soluble food and vitamins A, D, E, and K. Blood capillary is present that absorbs water-soluble food and vitamins B and C. Crypts of Lieberkuhn are intestinal glands present between two villi. They release intestinal juice ( Succus entericus) that helps in the digestion of fats, proteins, carbohydrates, and nucleic acids.

Large intestine

• It is a 1.5m long tube that extends from the Small intestine to the anus.
• It extends from the ileocaecal valve to the inner anal sphincter. It is wider and smaller than the small intestine.
• It is divided into three parts-

Caecum: ​It is also known as a Blind sac. In Caecum, the Vermiform appendix is present which is a vestigial lymphoid organ. Symbiotic microbes are also present in the caecum helps:

• In the formation of vitamin K and some vitamin B.
• In maintaining local immunity.
• In fermentation of undigested food.

Colon: The Colon is further divided into four regions, namely, ascending colon, transverse colon, descending colon, and sigmoid colon. It is made up of three longitudinal muscles (known as 'Taenia Coli') and circular muscles. It is divided into smaller units known as ''.

Rectum: It stores undigested fermented food.