Digestive enzyme
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2008-07-10T00:14:32Z
La Pianista
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Reverted edits by [[Special:Contributions/203.41.10.1|203.41.10.1]] to last version by Arcadian (using [[WP:HG|Huggle]])
<!-- where possible, the enzymes should be sorted according to their relative importance and the sequence of acting -->
'''Digestive enzymes''' are [[enzymes]] in the [[alimentary canal]] that break down [[food]] so that the [[organism]] can absorb it.<ref name="urlHerb Blurb: Digestive Enzymes">{{cite web |url=http://healthlink.mcw.edu/article/971119645.html |title=Herb Blurb: Digestive Enzymes |format= |work= |accessdate=}}</ref> The main sites of action are the [[oral cavity]], the [[stomach]], the [[duodenum]] and the [[jejunum]]. They are secreted by different glands: the [[salivary gland]]s, the glands in the [[stomach]], the [[pancreas]], and the glands in the [[small intestine]]s. <!-- but not liver! -->
==Oral cavity==
In the [[oral cavity]], [[salivary glands]] secrete [[ptyalin]]. It is a type of [[amylase|α-amylase]], which digests starch into small segments of multiple [[sugar]]s and into the individual soluble sugars. Secreted by small and large [[salivary glands]].
Salivary glands also secrete [[lysozyme]], which kills [[bacterium|bacteria]] but is not classified as a digestive enzyme.
==Stomach==
The enzymes that get secreted in the [[stomach]] are called '''gastric enzymes'''. These are the following:
*[[Pepsin]] is the main gastric enzyme. As it breaks [[protein]]s into smaller [[peptide]] fragments, it is a [[peptidase]].
*[[Gelatinase]], degrades type I and type V [[gelatin]] and type IV and V [[collagen]], which are [[proteoglycan]]s in meat.
*[[Amylase|Gastric amylase]] degrades starch, but is of minor significance.
*[[Lipase|Gastric lipase]] is a [[tributyrase]] by its biochemical activity, as it acts almost exclusively on [[tributyrin]], a butter fat enzyme.
==Small intestine==
===Pancreatic enzymes===
The [[pancreas]] is the main digestive gland in our body. It secretes the enzymes:
*[[Trypsin]], is a peptidase, that breaks down peptides in the small intestine.
*[[Chymotrypsin]], also a peptidase
*[[Steapsin]], degrades triglycerides into fatty acids and glycerol.
*[[Carboxypeptidase]], splits peptide fragments into individual [[amino acid]]s. It is a [[protease]].
*Several [[elastase]]s that degrade the protein [[elastin]] and some other proteins.
*Several [[nuclease]]s that degrade nucleic acids, like [[DNAase]] and [[RNAase]]
*[[amylase|Pancreatic amylase]] that, besides starch, [[glycogen]] and [[cellulose]], degrades most other carbohydrates.
*[[Bile]] from the liver, which emulsifies fat, allowing more efficient use of lipases in the duodenum; in converting lipids to their component fatty acid and glycerol molecules
===Proper small intestine enzymes===
*Several peptidases.
*The [[jejunum]] and [[ileum]] secretes a juice called [[succus entericus]] which contains the following:
Six types of enzymes degrade disaccharides into [[monosaccharide]]s:
*[[Sucrase]], which breaks down [[sucrose]] into [[glucose]] and [[fructose]]
*[[Maltase]], which breaks down [[maltose]] into [[glucose]].
*[[Isomaltase]], which breaks down [[maltose]] and [[isomaltose]]
*[[Lactase]], which breaks down [[lactose]] into [[glucose]] and [[galactose]]
*[[Lipase|Intestinal lipase]], which breaks down [[fatty acid]]s
The small intestine receives lipase, trypsin and amylase from the pancreas. They are transported from the pancreas to the duodenum through the pancreatic duct. Protein, fats and starch are broken down into smaller molecules. However, they are not fully broken down yet. This causes the enzymes of the small intestine to act upon them. These enzymes include peptidase, which breaks down peptides into amino acids and the enzyme maltase acts upon maltose which produces glucose. These molecules are absorbed by the villi in the small intestine and according to the molecule they are either absorbed by the lacteal or blood capillaries.
==References==
{{reflist}}
[[Category:Enzymes]]
{{Enzyme-stub}}
{{med-stub}}
{{Digestive enzymes}}
{{Serine endopeptidases}}
[[de:Verdauungsenzym]]
[[ja:消化酵素]]
[[ru:Ферменты пищеварения]]