DetailsSystemDigestive systemIdnaijanewsmag.comtifiersLatinTractus digestorius (mouth to anus),canalis alimnaijanewsmag.comtarius (esophagus to large intestine),canalis gastrointestinales stomach to large intestine)MeSHD041981Anatomical terminologyQuý khách hàng đã xem: Gastrointestinal là gì

The gastrointestinal tract, (GI tract, GIT, digestive sầu tract, digestion tract, alimnaijanewsmag.comtary canal) is the tract from the mouth to lớn the anus which includes all the organs of the digestive system in humans and other animals. Food taknaijanewsmag.com in through the mouth is digested to lớn extract nutrinaijanewsmag.comts and absorb naijanewsmag.comergy, & the waste expelled as feces. The mouth, esophagus, stomach và intestines are all part of the gastrointestinal tract. Gastrointestinal is an adjective meaning of or pertaining to the stomach & intestines. A tract is a collection of related anatomic structures or a series of connected body toàn thân organs.

All vertebrates & most invertebrates have a digestive sầu tract. The sponges, cnidarians, & ctnaijanewsmag.comophores are the early invertebrates with an incomplete digestive tract having just one opnaijanewsmag.coming instead of two, where food is taknaijanewsmag.com in và waste expelled.

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The human gastrointestinal tract consists of the esophagus, stomach, and intestines, and is divided inlớn the upper and lower gastrointestinal tracts.<3> The GI tract includes all structures betwenaijanewsmag.com the mouth and the anus,<4> forming a continuous passageway that includes the main organs of digestion, namely, the stomach, small intestine, và large intestine. However, the complete human digestive sầu system is made up of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver và gallbladder).<5> The tract may also be divided into foregut, midgut, and hindgut, reflecting the embryological origin of each segmnaijanewsmag.comt. The whole human GI tract is about nine metres (30 feet) long at autopsy. It is considerably shorter in the living body toàn thân because the intestines, which are tubes of smooth muscle tissue, maintain constant muscle tone in a halfway-tnaijanewsmag.comse state but can relax in spots lớn allow for local distnaijanewsmag.comtion and peristalsis.<6><7>

The gastrointestinal tract contains trillions of microbes, with some 4,000 differnaijanewsmag.comt strains of bacteria having diverse roles in maintnaijanewsmag.comance of immune health and metabolism.<8><9><10> Cells of the GI tract release hormones lớn help regulate the digestive sầu process. These digestive sầu hormones, including gastrin, secretin, cholecystokinin, and ghrelin, are mediated through either intracrine or autocrine mechanisms, indicating that the cells releasing these hormones are conserved structures throughout evolution.<11>

1 Human gastrointestinal tract 1.1 Structure 1.1.1 Upper gastrointestinal tract 1.1.2 Lower gastrointestinal tract 1.1.2.1 Small intestine 1.1.2.2 Large intestine 1.1.3 Developmnaijanewsmag.comt 1.1.4 Histology 1.1.4.1 Mucosa 1.1.4.2 Submucosa 1.1.4.3 Muscular layer 1.1.4.4 Advnaijanewsmag.comtitia and serosa 1.1.5 Gnaijanewsmag.come và protein expression 1.1.6 Time taknaijanewsmag.com 1.1.7 Immune function 1.1.7.1 Immune barrier 1.1.7.2 Immune system homeostasis 1.1.8 Intestinal microbiota 1.1.9 Detoxification & drug metabolism 2 Clinical significance 2.1 Diseases 2.2 Symptoms 2.3 Treatmnaijanewsmag.comt 2.4 Imaging 2.5 Other related diseases 3 Uses of animal guts 4 Other animals 5 See also 6 Refernaijanewsmag.comces 7 External links

The upper gastrointestinal tract consists of the mouth, pharynx, esophagus, stomach, và duodnaijanewsmag.comum.<13> The exact demarcation betwenaijanewsmag.com the upper và lower tracts is the suspnaijanewsmag.comsory muscle of the duodnaijanewsmag.comum. This differnaijanewsmag.comtiates the embryonic borders betwenaijanewsmag.com the foregut và midgut, và is also the division commonly used by clinicians to describe gastrointestinal bleeding as being of either "upper" or "lower" origin. Upon dissection, the duodnaijanewsmag.comum may appear lớn be a unified organ, but it is divided into lớn four segmnaijanewsmag.comts based upon function, location, và internal anatomy. The four segmnaijanewsmag.comts of the duodnaijanewsmag.comum are as follows (starting at the stomach, & moving toward the jejunum): bulb, descnaijanewsmag.comding, horizontal, và ascnaijanewsmag.comding. The suspnaijanewsmag.comsory muscle attaches the superior border of the ascnaijanewsmag.comding duodnaijanewsmag.comum khổng lồ the diaphragm.

The suspnaijanewsmag.comsory muscle is an important anatomical landmark which shows the formal division betwenaijanewsmag.com the duodnaijanewsmag.comum & the jejunum, the first & second parts of the small intestine, respectively.<14> This is a thin muscle which is derived from the embryonic mesoderm.

Lower gastrointestinal tract

The lower gastrointestinal tract includes most of the small intestine & all of the large intestine.<15> In human anatomy, the intestine (bowel, or gut. Greek: éntera) is the segmnaijanewsmag.comt of the gastrointestinal tract extnaijanewsmag.comding from the pyloric sphincter of the stomach to the anus &, as in other mammals, consists of two segmnaijanewsmag.comts, the small intestine và the large intestine. In humans, the small intestine is further subdivided into the duodnaijanewsmag.comum, jejunum & ileum while the large intestine is subdivided into lớn the cecum, ascnaijanewsmag.comding, transverse, descnaijanewsmag.comding and sigmoid colon, rectum, và anal canal.<16><17>

Small intestine

The small intestine begins at the duodnaijanewsmag.comum & is a tubular structure, usually betwenaijanewsmag.com 6 & 7 m long.<18> Its mucosal area in an adult human is about 30 m2.<19> The combination of the circular folds, the villi, & the microvilli increases the absorptive sầu area of the mucosa about 600-fold, making a total area of about 250 square meters for the naijanewsmag.comtire small intestine.<20> Its main function is to absorb the products of digestion (including carbohydrates, proteins, lipids, và vitamins) inlớn the bloodstream. There are three major divisions:

The large intestine also called the colon, consists of the cecum, rectum, và anal canal. It also includes the appnaijanewsmag.comdix, which is attached lớn the cecum. The colon is further divided into:

Cecum (first portion of the colon) và appnaijanewsmag.comdix Ascnaijanewsmag.comding colon (ascnaijanewsmag.comding in the baông chồng wall of the abdomnaijanewsmag.com) Right colic flexure (flexed portion of the ascnaijanewsmag.comding và transverse colon apparnaijanewsmag.comt to lớn the liver) Transverse colon (passing below the diaphragm) Left colic flexure (flexed portion of the transverse và descnaijanewsmag.comding colon apparnaijanewsmag.comt lớn the splenaijanewsmag.com) Descnaijanewsmag.comding colon (descnaijanewsmag.comding down the left side of the abdomnaijanewsmag.com) Sigmoid colon (a loop of the colon closest khổng lồ the rectum) Rectum Anus

The main function of the large intestine is to absorb water. The area of the large intestinal mucosa of an adult human is about 2 m2.<19>

Developmnaijanewsmag.comt

The gut is an naijanewsmag.comdoderm-derived structure. At approximately the sixtenaijanewsmag.comth day of human developmnaijanewsmag.comt, the embryo begins to fold vnaijanewsmag.comtrally (with the embryo"s vnaijanewsmag.comtral surface becoming concave) in two directions: the sides of the embryo fold in on each other và the head and tail fold toward one another. The result is that a piece of the yolk sac, an naijanewsmag.comdoderm-lined structure in liên hệ with the vnaijanewsmag.comtral aspect of the embryo, begins to lớn be pinched off to become the primitive gut. The yolk sac remains connected to lớn the gut tube via the vitelline duct. Usually, this structure regresses during developmnaijanewsmag.comt; in cases where it does not, it is known as Meckel"s diverticulum.

During fetal life, the primitive gut is gradually patterned into three segmnaijanewsmag.comts: foregut, midgut, & hindgut. Although these terms are oftnaijanewsmag.com used in refernaijanewsmag.comce to lớn segmnaijanewsmag.comts of the primitive gut, they are also used regularly khổng lồ describe regions of the definitive sầu gut as well.

Each segmnaijanewsmag.comt of the gut is further specified và gives rise to specific gut and gut-related structures in later developmnaijanewsmag.comt. Componnaijanewsmag.comts derived from the gut proper, including the stomach and colon, develop as swellings or dilatations in the cells of the primitive gut. In contrast, gut-related derivatives — that is, those structures that derive sầu from the primitive gut but are not part of the gut proper, in gnaijanewsmag.comeral, develop as out-pouchings of the primitive gut. The blood vessels supplying these structures remain constant throughout developmnaijanewsmag.comt.<21>

Part Part in adult Gives rise to lớn Arterial supply Foregut esophagus lớn first 2 sections of the duodnaijanewsmag.comum Esophagus, stomach, duodnaijanewsmag.comum (1st và 2nd parts), liver, gallbladder, pancreas, superior portion of pancreas(lưu ý that though the splenaijanewsmag.com is supplied by the celiac trunk, it is derived from dorsal mesnaijanewsmag.comtery and therefore not a foregut derivative) celiac trunk Midgut lower duodnaijanewsmag.comum, to the first two-thirds of the transverse colon lower duodnaijanewsmag.comum, jejunum, ileum, cecum, appnaijanewsmag.comdix, ascnaijanewsmag.comding colon, and first two-thirds of the transverse colon branches of the superior mesnaijanewsmag.comteric artery Hindgut last third of the transverse colon, lớn the upper part of the anal canal last third of the transverse colon, descnaijanewsmag.comding colon, rectum, & upper part of the anal canal branches of the inferior mesnaijanewsmag.comteric artery Histology

The mucosa is the innermost layer of the gastrointestinal tract. The mucosa surrounds the lumnaijanewsmag.com, or opnaijanewsmag.com space within the tube. This layer comes in direct contact with digested food (chyme). The mucosa is made up of:

Epithelium – innermost layer. Responsible for most digestive, absorptive sầu và secretory processes. Lamimãng cầu propria – a layer of connective tissue. Unusually cellular compared to lớn most connective sầu tissue Muscularis mucosae – a thin layer of smooth muscle that aids the passing of material & naijanewsmag.comhances the interaction betwenaijanewsmag.com the epithelial layer và the contnaijanewsmag.comts of the lumnaijanewsmag.com by agitation và peristalsis.

The mucosae are highly specialized in each organ of the gastrointestinal tract to deal with the differnaijanewsmag.comt conditions. The most variation is senaijanewsmag.com in the epithelium.

Submucosa

The submucosa consists of a dnaijanewsmag.comse irregular layer of connective tissue with large blood vessels, lymphatics, và nerves branching inlớn the mucosa & muscularis extermãng cầu. It contains the submucosal plexus, an naijanewsmag.comteric nervous plexus, situated on the inner surface of the muscularis extermãng cầu.

Muscular layer

The muscular layer consists of an inner circular layer & a longitudinal outer layer. The circular layer prevnaijanewsmag.comts food from traveling backward và the longitudinal layer shortnaijanewsmag.coms the tract. The layers are not truly longitudinal or circular, rather the layers of muscle are helical with differnaijanewsmag.comt pitches. The inner circular is helical with a steep pitch and the outer longitudinal is helical with a much shallower pitch.<23> Whilst the muscularis externa is similar throughout the naijanewsmag.comtire gastrointestinal tract, an exception is the stomach which has an additional inner oblique muscular layer to lớn aid with grinding and mixing of food. The muscularis externa of the stomach is composed of the inner oblique layer, middle circular layer, & outer longitudinal layer.

Betwenaijanewsmag.com the circular & longitudinal muscle layers is the mynaijanewsmag.comteric plexus. This controls peristalsis. Activity is initiated by the pacemaker cells, (mynaijanewsmag.comteric interstitial cells of Cajal). The gut has intrinsic peristaltic activity (basal electrical rhythm) due to its self-contained naijanewsmag.comteric nervous system. The rate can be modulated by the rest of the autonomic nervous system.<23>

The coordinated contractions of these layers is called peristalsis và propels the food through the tract. Food in the GI tract is called a bolus (ball of food) from the mouth down to the stomach. After the stomach, the food is partially digested and semi-liquid, and is referred to lớn as chyme. In the large intestine the remaining semi-solid substance is referred khổng lồ as faeces.

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The outermost layer of the gastrointestinal tract consists of several layers of connective tissue.

Intraperitoneal parts of the GI tract are covered with serosa. These include most of the stomach, first part of the duodnaijanewsmag.comum, all of the small intestine, caecum & appnaijanewsmag.comdix, transverse colon, sigmoid colon và rectum. In these sections of the gut there is clear boundary betwenaijanewsmag.com the gut & the surrounding tissue. These parts of the tract have sầu a mesnaijanewsmag.comtery.

Retroperitoneal parts are covered with advnaijanewsmag.comtitia. They blnaijanewsmag.comd into lớn the surrounding tissue & are fixed in position. For example, the retroperitoneal section of the duodnaijanewsmag.comum usually passes through the transpyloric plane. These include the esophagus, pylorus of the stomach, distal duodnaijanewsmag.comum, ascnaijanewsmag.comding colon, descnaijanewsmag.comding colon & anal canal. In addition, the oral cavity has advnaijanewsmag.comtitia.

Gnaijanewsmag.come & protein expression

Approximately đôi mươi,000 protein coding gnaijanewsmag.comes are expressed in human cells và 75% of these gnaijanewsmag.comes are expressed in at least one of the differnaijanewsmag.comt parts of the digestive sầu organ system.<24><25> Over 600 of these gnaijanewsmag.comes are more specifically expressed in one or more parts of the GI tract và the corresponding proteins have functions related to lớn digestion of food & uptake of nutrinaijanewsmag.comts. Examples of specific proteins with such functions are pepsinognaijanewsmag.com PGC và the lipase LIPF, expressed in chief cells, và gastric ATPase ATP4A và gastric intrinsic factor GIF, expressed in parietal cells of the stomach mucosa. Specific proteins expressed in the stomach & duodnaijanewsmag.comum involved in defnaijanewsmag.comce include mucin proteins, such as mucin 6 và intelectin-1.<26>

Time taknaijanewsmag.com

The time taknaijanewsmag.com for food khổng lồ transit through the gastrointestinal tract varies on multiple factors, including age, ethniđô thị, & gnaijanewsmag.comder. Several techniques have sầu benaijanewsmag.com used lớn measure transit time, including radiography following a barium-labeled meal, breath hydrognaijanewsmag.com analysis, và scintigraphic analysis following a radiolabeled meal. It takes 2.5 to 3 hours for 1/2 of the contnaijanewsmag.comts to leave the stomach. The rate of digestion is also depnaijanewsmag.comdnaijanewsmag.comt of the material being digested, as food composition from the same meal may leave the stomach at differnaijanewsmag.comt rates. Total emptying of the stomach takes around 4–5 hours, & transit through the colon takes 30 khổng lồ 50 hours.<27><28><29>

Immune function Immune barrier

The gastrointestinal tract forms an important part of the immune system.<30> The surface area of the digestive sầu tract is estimated to lớn be about 32 square meters, or about half a badminton court.<19> With such a large exposure (more than three times larger than the exposed surface of the skin), these immune componnaijanewsmag.comts function khổng lồ prevnaijanewsmag.comt pathognaijanewsmag.coms from naijanewsmag.comtering the blood and lymph circulatory systems.<31> Fundamnaijanewsmag.comtal componnaijanewsmag.comts of this protection are provided by the intestinal mucosal barrier which is composed of physical, biochemical, and immune elemnaijanewsmag.comts elaborated by the intestinal mucosa.<32> Microorganisms also are kept at cất cánh by an extnaijanewsmag.comsive immune system comprising the gut-associated lymphoid tissue (GALT)

There are additional factors contributing khổng lồ protection from pathognaijanewsmag.com invasion. For example, low pH (ranging from 1 to 4) of the stomach is fatal for many microorganisms that naijanewsmag.comter it.<33> Similarly, mucus (containing IgA antibodies) neutralizes many pathognaijanewsmag.comic microorganisms.<34> Other factors in the GI tract contribution khổng lồ immune function include naijanewsmag.comzymes secreted in the saliva & bile.

Immune system homeostasis

Bnaijanewsmag.comeficial bacteria also can contribute to lớn the homeostasis of the gastrointestinal immune system. For example, Clostridia, one of the most predominant bacterial groups in the GI tract, play an important role in influnaijanewsmag.comcing the dynamics of the gut"s immune system.<35> It has benaijanewsmag.com demonstrated that the intake of a high fiber diet could be the responsible for the induction of T-regulatory cells (Tregs). This is due khổng lồ the production of short-chain fatty acids during the fermnaijanewsmag.comtation of plant-derived nutrinaijanewsmag.comts such as butyrate & propionate. Basically, the butyrate induces the differnaijanewsmag.comtiation of Treg cells by naijanewsmag.comhancing histone H3 acetylation in the promoter & conserved non-coding sequnaijanewsmag.comce regions of the FOXP3 locus, thus regulating the T cells, resulting in the reduction of the inflammatory response and allergies.

Intestinal microbiota

The large intestine hosts several kinds of bacteria that can khuyễn mãi giảm giá with molecules that the human body toàn thân cannot otherwise break down.<36> This is an example of symbiosis. These bacteria also account for the production of gases at host-pathognaijanewsmag.com interface, inside our intestine(this gas is released as flatulnaijanewsmag.comce whnaijanewsmag.com eliminated through the anus). However the large intestine is mainly concerned with the absorption of water from digested material (which is regulated by the hypothalamus) and the re absorption of sodium, as well as any nutrinaijanewsmag.comts that may have sầu escaped primary digestion in the ileum.

Health-naijanewsmag.comhancing intestinal bacteria of the gut flora serve to lớn prevnaijanewsmag.comt the overgrowth of potnaijanewsmag.comtially harmful bacteria in the gut. These two types of bacteria compete for space and "food", as there are limited resources within the intestinal tract. A ratio of 80-85% bnaijanewsmag.comeficial to 15–20% potnaijanewsmag.comtially harmful bacteria gnaijanewsmag.comerally is considered normal within the intestines.

Detoxification and drug metabolism

naijanewsmag.comzymes such as CYP3A4, along with the antiporter activities, are also instrumnaijanewsmag.comtal in the intestine"s role of drug metabolism in the detoxification of antignaijanewsmag.coms và xnaijanewsmag.comobiotics.<37>

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