For meat and the starch in the

For lunch I ate rice, meat, vegetables, and drank water. The rice, meat, and vegetables would undergo mechanical digestion, in which they would be broken up into smaller pieces. This increases the surface area for enzymatic action, increasing the rate of chemical digestion of the food. ?The water consumed would flow through the digestive system undigested. Reaching the small and large intestines where they would be absorbed. (mainly absorbed by the large intestine) The vegetables I ate contains an insoluble fiber called cellulose that the body is unable to digest as we do not produce cellulase. Cellulose acts a natural dietary fiber that aids in the movement of food down the digestive system. Because it remains undigested, cellulose forms the main bulk of stool and helps with excretion. Despite not undergoing chemical digestion, the vegetables would still undergo mechanical digestion. The vitamins contained within the vegetables would be able to dissolve out, to be absorbed by small intestine. The digestion for the protein in the meat and the starch in the rice goes as follows.?In the mouth, the food would be broken up into smaller pieces through mastication. Salivary amylase is secreted by salivary glands, and would act on the starch found in the rice, breaking it down into maltose. The tongue would roll the rice and meat into a bolus that would be directed down to the pharynx and the esophagus. The meat would would remain chemically undigested as protease is absent.?Through the pharynx and esophagus, no further digestion occurs due to lack of enzymes.?In the stomach, peristalsis occurs to further break up the food particles into smaller pieces and to combine it with gastric juices to form chyme.  The parietal cells secretes hydrochloric acid, and the chief cells secretes inactive pepsinogen that activates in the presence of hydrochloric acid to form active pepsin. This active pepsin breaks down the proteins found in the ingested meat into polypeptides. Gastric amylase provides minimal digestion of the starch found in the rice.?In the small intestine, mechanical digestion occurs in the form of segmentation where food particles are mixed and churned. This increases the rate of chemical digestion, and facilitates the absorption of digested food in the small intestine as the digested food is pressed into the walls of the small intestine. For chemical digestion, inactive trypsinogen is secreted by the pancreas into the small intestine where it is activated by the enteropeptidase found within the intestinal mucosa to form active trypsin. Active trypsin breaks down the polypeptide into amino acids. Maltase is found as brush border enzyme, and breaks down the maltose into glucose. The amino acids and glucose are transported from the lumen of the small intestine, through the epithelial cells of the villi, and into the capillaries lining the small intestine where they would be transported to the rest of the body.


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