Large intestine and small intestine both are part of our digestive system. But they differ not only functionally but structurally as well. For example: small intestine is the longest part of our digestive tract which measures about 4-7m while large intestine is only 1-2m long. Large intestine is called large because of its diameter which is wider as compared to small intestine.
When we talk about their functions small intestine is the main part of our digestive tract to absorb maximum nutrients from our food while large intestine absorbs water and electrolytes.
What is Small Intestine?
Small intestine is present between stomach and large intestine. Being the longest part of our digestive tract its main function is to absorb maximum nutrients from our food. For absorption it has special microscopic finger-like projections called villi. Villi increases the surface area of the small intestine so maximum nutrients are available for absorption. Small intestine is divided into three parts duodenum, jejunum, and ileum.
Duodenum is the smallest part and starts from the end of stomach. Duodenum has a common opening from pancreas and biliary system which allows digestive secretions to flow into it and help to break down proteins and emulsify fats. Iron is also absorbed in duodenum. Jejunum is the midst part of small intestine. A suspensory muscle of duodenum marks the division of duodenum and jejunum. Here in jejunum digested products are absorbed through villi. After jejunum the last part of small intestine, ileum starts. Ileum mainly absorbs the remaining nutrients, bile salts and vitamin B12. Ileum then ends into large intestine.
What is Large Intestine?
Also called colon. Large intestine starts from the end of small intestine. It is called large intestine because of its diameter. Large intestine is divided into caecum, colon, rectum and anus. Colon consist of four sections named ascending colon, transverse colon, descending colon and sigmoid colon. Its main function is to absorb water and salt from the products of digestion. It can store remaining product as feces. Large intestine have no role in absorption of nutrients from food because they lack villi. Appendix, a vestigial organ is attached to caecum.
Large intestine contains micro flora which helps in formation of vitamins such as vitamin K, vitamin B12, vitamin B1, vitamin B2. The surface of large intestine contains bands of longitudinal muscles called taeniae coli. Taeniae coli starts form the base of appendix and extends up to the rectum. The haustra are small sacculations present in the large intestine which differentiates it from small intestine. Haustra basically are bulges due to contraction of taeniae coli. Large intestine have no movement but have smooth muscles which contracts and relax that works until the food expels out from the body through anus.
Key Differences between Small Intestine and Large Intestine
- Small intestine is the longest part of digestive tract measures about 7m while large intestine measures about 2m.
- Small intestine has narrow diameter as compared to large intestine which has a diameter around 4-6cm.
- Small intestine main function is to absorb nutrients from the food while large intestine absorb water, salts and store feces.
- Small intestine have microscopic finger-like projections called villi while in large intestine villi are absent.
- Small intestine is divided into duodenum, jejunum, ileum while large intestine is divided into caecum, colon, rectum and anus.
- Haustrations are present in large intestine but are absent in small intestine.