Digestion/ Absorption and Homeostasis
In order to survive, our bodies must bring in energy and nutrients for the cells of the body through eating and digestion of food. To be carried to the cells of the body by the blood stream, food must be broken down to molecules. This breaking down of food into molecules, small enough to be absorbed into and carried through the blood stream, is carried out by the digestive system through the process of digestion and absorption. Digestion is the process of turning food into usable sources of energy. During the process of absorption, nutrients that come from the food, including carbohydrates, proteins, fats, vitamins, and minerals, pass through channels in the intestinal wall and into the bloodstream. “Organs that make up the digestive tract are the mouth, esophagus, stomach, small intestine, large intestine—also called the colon—rectum, and anus” (NDDIC). Digestion begins in the mouth, where the food is cut and ground into small pieces. As the food is broken up, the first phase of chemical digestion occurs as saliva, which is secreted from the salivary glands. Amylase, contained in the saliva, begins the breakdown of starches into sugar. Once the food is softened by the saliva and swallowed into the esophagus, a muscular action, called peristalsis, helps to then push the food down the esophagus and into the stomach. When the food reaches the stomach, the chemical breakdown process continues where “the stomach secretes gastric juice, which is made up of a protein-digesting enzyme, mucus, and strong acid” (Reece, Taylor, Simon, & Dickey, 2012, p. 436) The result of this process occurring in the stomach produces a thick acidic liquid called chyme, which is the partially digested food and the digestive secretions. Peristaltic waves will continue to push the chyme toward the small intestine. The small intestine has two major functions; to break down food into smaller molecules and to absorb these molecules into the blood...
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