The small intestine is a long and narrow coiled tube that extends from the stomach to the large intestine, winding around within the abdomen. Small and large refer to the diameter, which for the small intestine is about 2.5-3 cm (~1″) compared to 6.5-7 cm (~2.5″) for the large intestine. The names of these parts are a bit confusing, as the small intestine is about three times as long as the large intestine. The lower part of the GI tract includes the small and large intestines. Strong chemicals break food down into smaller components, while the stomach’s thick walls keep these chemicals from entering the body as it squeezes its contents with strong circular and longitudinal muscles. It increases in diameter as it receives food, holding up to a maximum of about 4 litres (but do not eat so much as to extend the stomach fully). The composition and quantity of dietary intake, the presence of a GI disease or disorder, and other factors influence transit time.įollowing the esophagus, located within the left side of the abdominal cavity, is the stomach, a sac-like organ about 25 cm (~10″) long. Some individuals have an irregular pattern, never knowing what to expect. Each person is unique a normal bowel movement pattern for one person may be very different from those of family members or friends. A meal could take anywhere from 12-72 hours to travel through the digestive tract. Transit time is the duration between when you take a bite of your meal and when leftover waste finally passes out as stool (feces). If all is going well, the passage of food from one area of the intestines to the next is precisely coordinated, so that it stays in each area for just the right amount of time. A number of body systems provide the chemicals necessary to complete digestion, absorption, and elimination. Chewing and swallowing (ingesting) require conscious effort, but once food reaches the esophagus, an automatic, rhythmic motion (peristalsis) takes over, propelling the contents along. In the mouth, chewing mechanically breaks down and mixes food, while saliva begins to modify it chemically, thus beginning the digestive process. ![]() The upper part of the GI tract includes the mouth, throat (pharynx), esophagus, and stomach. The dimensions mentioned below are for an average adult male. The size and shape of the digestive tract varies according to the individual (e.g., age, sex, size, and disease state). The digestive system consists of a long tube (alimentary canal) that varies in shape and purpose as it winds its way through the body from the mouth to the anus (see diagram). This explanation is not complete, but it covers the basics. To understand IBD, a review of gastrointestinal (GI) tract anatomy is helpful. Inflammatory Bowel Disease Intestinal Anatomy Lymphatic organs contain lymphocytes that destroy invading organisms.Click here to download a PDF of this information. Lymph nodes and other lymphatic organs filter the lymph to remove microorganisms and other foreign particles. The third and probably most well known function of the lymphatic system is defense against invading microorganisms and disease. The lymph in the lacteals has a milky appearance due to its high fat content and is called chyle. The blood capillaries absorb most nutrients, but the fats and fat-soluble vitamins are absorbed by the lacteals. There are blood capillaries and special lymph capillaries, called lacteals, in the center of each villus. The mucosa that lines the small intestine is covered with fingerlike projections called villi. The second function of the lymphatic system is the absorption of fats and fat- soluble vitamins from the digestive system and the subsequent transport of these substances to the venous circulation. After the fluid enters the lymph capillaries, it is called lymph. Lymph capillaries pick up the excess interstitial fluid and proteins and return them to the venous blood. If this continues, blood volume and blood pressure decrease significantly and the volume of tissue fluid increases, which results in edema (swelling). This further inhibits the return of fluid into the capillaries, and fluid tends to accumulate in the tissue spaces. Small protein molecules may "leak" through the capillary wall and increase the osmotic pressure of the interstitial fluid. The 10 percent that does not return becomes part of the interstitial fluid that surrounds the tissue cells. Of the fluid that leaves the capillary, about 90 percent is returned. First of all, it returns excess interstitial fluid to the blood. The lymphatic system has three primary functions. Acknowledgements Introduction to the Lymphatic System
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