Follow the digestive and absorptive process through the GI tract by describing the major events that occur in the mouth, stomach, small intestine, and colon. Include a discussion of the enzymes involved in digestion

Answer 1

?In the mouth, the food is chewed and mixed with saliva. Saliva contains enzymes that initiate the digestion of carbohydrates. In the stomach, gastric glands secrete gastric juice, a mixture of water, enzymes, and hydrochloric acid, which acts primarily in protein digestion. In the small intestine, pancreatic digestive juices act on all three energy nutrients (enzymes on the surfaces of the small intestine cells complete the process of breaking down starch for absorption through the intestinal wall and into the hepatic portal vein; pancreatic and intestinal lipases begin to break down fats for absorption through the intestinal wall and into the lymph; pancreatic and intestinal lipases break down proteins for absorption into the hepatic portal vein). Bile, an emulsifier that brings fats into suspension in water so enzymes can break them down into their component parts, is released into the small intestine. Most absorption takes place in the small intestine. By the time the contents of the GI tract reach the end of the small intestine, little remains but water, a few dissolved salts and body secretions, and undigested material such as fiber. In the colon, intestinal bacteria ferment some fibers and retrieve all materials that the body can recycle-water and dissolved salts.