The Digestive System: The Functions Of The Digestive System

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1. The digestive systems functions are to digest food, absorb any end products that were digested (including vitamins and minerals). The physiological processes of the digestive system are ingestion, propulsion, mechanical breakdown, digestion, absorption and defecation. Mechanical digestion means to use force in order to break down food for example the use of chewing or the contraction of muscles. Chemical digestion is when the food is broken down chemically into smaller particles such as the use of the saliva in the mouth.
2. The four tissue layers are the mucosa, submucosa, muscularis externa, and the serosa. The mucosa is the inner most layer which also composes of its own; the epithelial, lamina propia, and muscularis mucosa. The mucosa secretes hormones, digestive enzymes and also mucus as well. The submucosa is composed of areolar connective tissue, which contains a rich blood supply, nerve fibers and lymphatic vessels and follicles. The muscularis external is the layer that is responsible for the function of segmentation and peristalsis. It contains an inner circular layer and also an outer longitudinal layer both of smooth muscle cells. The serosa is the layer that is the outermost. It is also called the visceral peritoneum and it is areolar connective tissue that is covered with mesothelium.
3. The enteric nervous system is composed of intrinsic nerve plexuses, submucosal nerve plexuses, and myenteric nerve plexuses. The submucosal nerve plexuses are located in the submucosal. The myenteric nerve plexuses are located between the circular muscle layer and the longitudinal muscle layer. They provide an important nerve supply to the GI tract wall and also are in control of motility of the GI tract.
4. Neutral mechanism...

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...s in absorption. The mucosa of the small intestine also has a submucosa, which forms the plicae circulars, and it increases the surface area of the intestines.
14. The migrating motor complex (MMC) is described as strong and rhythmic contractions in the small intestines and the stomach during the fasting state. Segmentation is described as the contraction that is rhythmic in the small intestines which allows chyme to mix.
15. (NOT APPLICABLE)
16. The mucosa in the colon is composed of simple columnar epithelium and unlike the mucosa of the small intestine it contains no villi or plicae circularis . Although, it does contain crypts.
17. Haustral contractions occur by intervals of 30 minutes, they mix contents inside the intestine back and forth. Mass movements occur 3-4 times a day and they bring the contents in the large intestine towards the rectum to be stored.

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