Page 14 - LN-CH-16

* Infact, all these bacteria synthesise vitamin-K and B 12 , also helps in absorption of
calcium, magnesium and zinc (by increasing the acidity of colon region).
Followingfunctions areperformed by the large intestine
(i) Absorption of some water, minerals and certain drugs.
(ii) Secretion of mucus which helps in adhering the waste (undigested) particles
together and lubricating it for an easy passage.
No significant digestive activity occurs in this region of digestive tract. .
The undigested, unabsorbed substances called faeces, enters into the caecum
region of the large intestine (through the ileo-caecal valve, which prevents the back
flow of faecel matter). It is temporarily stored in the rectum till defecation (egestion)
through the anus.
Apart from absorbing vitamins secreted by various types of bacteria, large intestine
also helps in absorbing water and electrolytes such as Na , Cl .
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Neural and Hormonal Control of Digestion
For proper coordination- and functioning of different parts of the gastrointestinal
tract, it should be under a proper, neural and hormonal control.
Neural Control
Secretion of saliva is stimulated by the sight, smell and the presence of food in the
oral cavity. Similarly, the gastric and intestinal secretions are also under the control
of neural signals.
The muscular activities of different parts of the alimentary canal are also moderated
by neural mechanisms (both local and through CNS).
Hormonal Control
The major hormones that control the functions of digestive system are produced and
released by the cells in the mucosa of the stomach and the large intestine.