The gastrointestinal tract (digestive tract, digestional tract, GI tract, GIT, gut, or alimentary canal) is an organ system within humans and other animals which takes in food, digests it to extract and absorb energy and nutrients, and expels the remaining waste as feces. Page 1. Page 2. Page 3. Page 4. Page 5. Page 6. Page 7. Page 8. Page 9. In this review, the gross physiology of the gastrointestinal tract of dogs is compared with that of humans, particularly as it pertains to drug absorption and.


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  • Human Physiology/The gastrointestinal system - Wikibooks, open books for an open world
  • Comparison of canine and human gastrointestinal physiology.
  • Comparison of canine and human gastrointestinal physiology.

This layer comes in direct contact with digested food chyme. The mucosa is made up of: Epithelium human gastrointestinal physiology innermost layer. Responsible for most digestive, absorptive and secretory processes. Lamina propria — a layer of connective tissue.

Gastrointestinal tract

Unusually cellular compared to most connective tissue Muscularis mucosae — a thin layer of smooth muscle that aids the passing of material and enhances the interaction between the epithelial layer and the contents of the lumen by agitation and peristalsis.

The mucosae are highly specialized in each organ of the gastrointestinal tract to deal human gastrointestinal physiology the different conditions. The most variation is seen in the epithelium.


Submucosa The submucosa consists of a dense irregular layer of connective tissue with large blood vessels, lymphatics, and nerves branching into the mucosa and muscularis externa.

It contains the submucosal plexusan enteric nervous plexussituated on the inner surface of the muscularis externa. Muscular layer[ edit ] The muscular layer consists of an inner circular layer and a longitudinal outer layer.

The circular layer prevents food human gastrointestinal physiology traveling backward and the longitudinal human gastrointestinal physiology shortens the tract.

Gastrointestinal tract - Wikipedia

The layers are not truly longitudinal or circular, rather human gastrointestinal physiology layers of muscle are helical with different pitches. The inner circular is helical with a steep pitch and the outer longitudinal is helical with a much shallower pitch.

The muscularis externa of the stomach is composed of the inner oblique layer, middle circular layer and outer longitudinal layer. The greater omentum hangs from the greater curvature. A mucous membrane lines the stomach which contains glands with chief cells that secrete gastric juices, up to three quarts of this digestive fluid is produced daily.

The gastric glands begin secreting before food enters the stomach due to the parasympathetic impulses of the vagus nerve, making the stomach also a storage vat for that acid. The secretion of gastric juices occurs in three phases: The human gastrointestinal physiology phase is activated by the smell and taste of human gastrointestinal physiology and swallowing.

The gastric phase is activated by the chemical effects of food and the distension of the stomach. The intestinal phase blocks the effect of the cephalic and gastric phases.

Gastric juice also contains an enzyme named pepsin, which digests proteins, hydrochloric acid and mucus. Hydrochloric acid causes the stomach to maintain a pH of human gastrointestinal physiology 2, which helps kill off bacteria that comes into the digestive system via food.

Human Physiology/The gastrointestinal system

The gastric juice is highly acidic with a pH of It may cause or compound damage to the stomach wall or its layer of mucus, causing a peptic human gastrointestinal physiology.

On the inside of the stomach there are folds of skin call the gastric rugae.

Gastric rugae make the stomach very extendable, especially after a very big meal. The stomach is divided into four sections, each of which has different cells and functions.


Two smooth muscle valves, or sphincters, keep the contents of the stomach contained. After receiving the bolus chewed human gastrointestinal physiology the process of peristalsis is started; mixed and churned with gastric juices the bolus is transformed into a semi-liquid substance called chyme.

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Stomach muscles mix up the food with enzymes and acids to make smaller digestible pieces. The pyloric sphincter, a walnut shaped muscular tube at the human gastrointestinal physiology outlet, keeps chyme in the stomach until it reaches the right consistency to pass into the small intestine.


The food leaves the stomach in small squirts rather than all at once. Water, alcohol, salt, and simple sugars can be absorbed directly through the stomach wall.