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The mucosal immune system consists of a cellular component, humoral immunity, and defense mechanisms that prevent the invasion of microorganisms and harmful foreign substances into the body. These defense mechanisms can be divided into physical barriers ( epithelial lining , mucus , cilia function , intestinal peristalsis , etc.) and chemical ...
During the second week of development, the embryo grows and begins to surround and envelop portions of this sac. The enveloped portions form the basis for the adult gastrointestinal tract. Sections of this foregut begin to differentiate into the organs of the gastrointestinal tract, such as the esophagus, stomach, and intestines. [41]
The gut-associated lymphoid tissue lies throughout the intestine, covering an area of approximately 260–300 m 2. [5] In order to increase the surface area for absorption, the intestinal mucosa is made up of finger-like projections (), covered by a monolayer of epithelial cells, which separates the GALT from the lumen intestine and its contents.
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and other animals, including the esophagus , stomach , and intestines .
[13] [14] In the stomach, gastric acid serves as a chemical defense against ingested pathogens. [15] Within the genitourinary and gastrointestinal tracts, commensal flora serve as biological barriers by competing with pathogenic bacteria for food and space and, in some cases, changing the conditions in their environment, such as pH or available ...
The tonsils are a set of lymphoid organs facing into the aerodigestive tract, which is known as Waldeyer's tonsillar ring and consists of the adenoid tonsil (or pharyngeal tonsil), two tubal tonsils, two palatine tonsils, and the lingual tonsils. These organs play an important role in the immune system.
The gastrointestinal wall is inflamed in a number of conditions. This is called esophagitis , gastritis , duodenitis , ileitis , and colitis depending on the parts affected. It can be due to infections or other conditions, including coeliac disease , and inflammatory bowel disease affects the layers of the gastrointestinal tract in different ways.
It can be caused by damage to an organ, or from a contusion to the abdominal wall from the outside or by surgery. It may be brought in by the bloodstream or the lymphatic system. The most common origin is the gastrointestinal tract. Peritonitis can be acute or chronic, generalized or localized, and may have one origin or multiple origins.