Discuss motility of the digestive tract by explaining the differences between peristalsis and ...

Answer to #1

Motility is the spontaneous movement of the GI tract muscles. Peristalsis is the wavelike muscular contractions of the GI tract that push its contents along. Segmentation is a periodic squeezing or partitioning of the intestine at intervals along its length by its circular muscles. Sphincter muscles periodically open and close, allowing the contents of the GI tract to move along at a controlled pace. The upper esophageal sphincter opens in response to swallowing; the lower esophageal sphincter (also called the cardiac sphincter) prevents reflux of stomach contents; the pyloric sphincter holds chyme in the stomach long enough to be liquefied and prevents intestinal contents from backing up into the stomach; the ileocecal valve allows the contents of the small intestine to empty into the large intestine; two sphincters of the anus prevent continuous elimination.

Answer to #2

B

Answer to #3

TRUE

Answer to #4

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.

Answer to #5

TRUE

Answer to #6

D

Answer to #7

The process of digestion begins in the mouth. Fluids help dissolved the food so that the tongue can taste it; only particles in solution can react with taste buds. When stimulated, the taste buds detect one, or a combination, of the five basic taste sensations: sweet, sour, bitter, salty, and umami. In addition to these chemical triggers, aroma, appearance, texture, and temperature also affect a food's flavor.

Answer to #8

FALSE