Give functions of large intestine?
Answers
Large intestine absorbs water from the unabsorbed food and the bacteria present here converts unabsorbed food into faecal matter
ARTICLE
Large intestine function
Recent research has revealed that the large intestine and its resident bacterial population have key roles to play in determining our health and wellbeing. It is much more than just a waste storage facility.
Structural features
In an average adult, the large intestine is about 1.5m long and 5cm wide. It consists of the caecumappendixcolon and rectum.
The large intestine
The large intestine consists of the caecum, colon, rectum and anal canal. It is about 1.5 metres long and has an average diameter of about 6 cm.
The 4 major functions of the large intestine are recovery of water and electrolytes, formation and storage of faeces and fermentation of some of the indigestible food matter by bacteria.
The ileocaecal valve controls the entry of material from the last part of the small intestine called the ileum.
The human appendix has no known function and is thought to be a remnant from a previous time in human evolution.
What does the large intestine do?
The 4 major functions of the large intestine are:
reabsorption of water and mineral ions such as sodium and chloride
formation and temporary storage of faeces
maintaining a resident population of over 500 species of bacteria
bacterial fermentation of indigestible materials.
By the time partially digested foodstuffs reach the end of the small intestine (ileum), about 80% of the water content has been absorbed. The colon absorbs most of the remaining water.
As the remnant food material moves through the colon, it is mixed with bacteria and mucus, and formed into faeces for temporary storage before being eliminated.
It has been estimated that there are about 500 species of different bacteria found inhabiting the adult colon. Most of these bacteria can only survive in oxygen-free environments and are referred to as anaerobes. These bacteria ferment some of the undigested food components, converting them into short-chain fatty acids (SCFAs) and releasing gases like carbon dioxidehydrogen and methane. SCFAs such as acetic, propanoic and butyric acids then serve as an energy source for the bacteria as well as the cells lining the colon.
CH3COOH
acetic acid
CH3CH2COOH
propanoic acid
CH3CH2CH2COOH
butyric acid
Gut bacteria and health
The resident bacterial species in the large intestine form complex inter-relationships with themselves as well as their human host. It is now thought that, rather than being a non-harmful coexistence, it is in fact a symbiotic relationship where each gains benefit from the other.