Difference between revisions of "Digestion"
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==Origin== | ==Origin== | ||
[[Latin]] ''dīgest''-, participial stem of ''dīger-ĕre'' to carry asunder, [[separate]], divide, [[distribute]], [[dissolve]] | [[Latin]] ''dīgest''-, participial stem of ''dīger-ĕre'' to carry asunder, [[separate]], divide, [[distribute]], [[dissolve]] | ||
| − | *[ | + | *[https://en.wikipedia.org/wiki/14th_century 14th Century] |
==Definitions== | ==Definitions== | ||
*1 : the [[process]] of making [[food]] absorbable by [[dissolving]] it and breaking it down into [[simpler]] [[chemical]] compounds that occurs in the living body chiefly through the [[action]] of enzymes secreted into the alimentary canal | *1 : the [[process]] of making [[food]] absorbable by [[dissolving]] it and breaking it down into [[simpler]] [[chemical]] compounds that occurs in the living body chiefly through the [[action]] of enzymes secreted into the alimentary canal | ||
*2 : the process in sewage treatment by which [[organic]] [[matter]] in sludge is decomposed by anaerobic bacteria with the release of a burnable mixture of [[gases]] | *2 : the process in sewage treatment by which [[organic]] [[matter]] in sludge is decomposed by anaerobic bacteria with the release of a burnable mixture of [[gases]] | ||
==Description== | ==Description== | ||
| − | '''Digestion''' is the [[mechanical]] and [[chemical]] breakdown of [[food]] into smaller components that are more easily absorbed into a [[blood]] stream, for instance. Digestion is a form of [ | + | '''Digestion''' is the [[mechanical]] and [[chemical]] breakdown of [[food]] into smaller components that are more easily absorbed into a [[blood]] stream, for instance. Digestion is a form of [https://en.wikipedia.org/wiki/Catabolism catabolism]: a breakdown of large food [[molecules]] to smaller ones. |
| − | When [[food]] enters the mouth, its digestion starts by the action of [ | + | When [[food]] enters the mouth, its digestion starts by the action of [https://en.wikipedia.org/wiki/Mastication mastication], a form of [[mechanical]] digestion, and the contact of [[saliva]]. Saliva, which is secreted by the [https://en.wikipedia.org/wiki/Salivary_glands salivary glands], contains [https://en.wikipedia.org/wiki/Salivary_amylase salivary amylase], an enzyme which starts the digestion of starch in the food. After undergoing mastication and starch digestion, the food will now be in the form of a small, round mass, called a Bolus (It will then travel down the [https://en.wikipedia.org/wiki/Esophagus esophagus] and into the stomach by the [[action]] of [https://en.wikipedia.org/wiki/Peristalsis peristalsis]. [https://en.wikipedia.org/wiki/Gastric_juice Gastric juice] in the stomach starts protein digestion. Gastric juice mainly contains [https://en.wikipedia.org/wiki/Hydrochloric_acid hydrochloric acid] and [https://en.wikipedia.org/wiki/Pepsin pepsin]. As these two [[chemicals]] may damage the stomach wall, [https://en.wikipedia.org/wiki/Mucus mucus] is secreted by the stomach, providing a slimy layer that acts as a shield against the damaging [[effects]] of the chemicals. At the same time protein digestion is occurring, [[mechanical]] mixing occurs by peristalsis, which are [[waves]] of muscular contractions that move along the stomach wall. This allows the mass of [[food]] to further mix with the digestive enzymes. After some time (typically an hour or two in humans, 4–6 hours in dogs, somewhat shorter duration in house cats), the resulting thick liquid is called [https://en.wikipedia.org/wiki/Chyme chyme]. When the [https://en.wikipedia.org/wiki/Pylorus pyloric sphincter valve] opens, chyme enters the [https://en.wikipedia.org/wiki/Duodenum duodenum] where it mixes with digestive enzymes from the [https://en.wikipedia.org/wiki/Pancreas pancreas], and then passes through the [https://en.wikipedia.org/wiki/Small_intestine small intestine], in which digestion continues. When the chyme is fully digested, it is [[absorbed]] into the [[blood]]. 95% of absorption of nutrients occurs in the small intestine. Water and minerals are reabsorbed back into the blood in the [https://en.wikipedia.org/wiki/Colon_(anatomy) colon] (large intestine). Some vitamins, such as [https://en.wikipedia.org/wiki/Biotin biotin] and [https://en.wikipedia.org/wiki/Vitamin_K vitamin K] (K2MK7) produced by bacteria in the colon are also absorbed into the blood in the colon. [[Waste]] material is eliminated during [https://en.wikipedia.org/wiki/Defecation defecation].[https://en.wikipedia.org/wiki/Digestion] |
[[Category: Biology]] | [[Category: Biology]] | ||
[[Category: Health]] | [[Category: Health]] | ||
Latest revision as of 01:14, 13 December 2020
Origin
Latin dīgest-, participial stem of dīger-ĕre to carry asunder, separate, divide, distribute, dissolve
Definitions
- 1 : the process of making food absorbable by dissolving it and breaking it down into simpler chemical compounds that occurs in the living body chiefly through the action of enzymes secreted into the alimentary canal
- 2 : the process in sewage treatment by which organic matter in sludge is decomposed by anaerobic bacteria with the release of a burnable mixture of gases
Description
Digestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones.
When food enters the mouth, its digestion starts by the action of mastication, a form of mechanical digestion, and the contact of saliva. Saliva, which is secreted by the salivary glands, contains salivary amylase, an enzyme which starts the digestion of starch in the food. After undergoing mastication and starch digestion, the food will now be in the form of a small, round mass, called a Bolus (It will then travel down the esophagus and into the stomach by the action of peristalsis. Gastric juice in the stomach starts protein digestion. Gastric juice mainly contains hydrochloric acid and pepsin. As these two chemicals may damage the stomach wall, mucus is secreted by the stomach, providing a slimy layer that acts as a shield against the damaging effects of the chemicals. At the same time protein digestion is occurring, mechanical mixing occurs by peristalsis, which are waves of muscular contractions that move along the stomach wall. This allows the mass of food to further mix with the digestive enzymes. After some time (typically an hour or two in humans, 4–6 hours in dogs, somewhat shorter duration in house cats), the resulting thick liquid is called chyme. When the pyloric sphincter valve opens, chyme enters the duodenum where it mixes with digestive enzymes from the pancreas, and then passes through the small intestine, in which digestion continues. When the chyme is fully digested, it is absorbed into the blood. 95% of absorption of nutrients occurs in the small intestine. Water and minerals are reabsorbed back into the blood in the colon (large intestine). Some vitamins, such as biotin and vitamin K (K2MK7) produced by bacteria in the colon are also absorbed into the blood in the colon. Waste material is eliminated during defecation.[1]
