Exam 29: A: Physiology of the Digestive System

The primary function of the digestive system is to bring essential nutrients into the internal environment so that they are available to the cells of the body.

Most enzymes are able to catalyze reactions in both directions,but that rarely occurs in digestive enzymes.

The lipase found in saliva is unable to digest much fat because the fat has not been emulsified.

Vasoactive intestinal peptide inhibits the production of intestinal juice.

To properly regulate the flow of food from the stomach to the small intestine,a balance is maintained between gastric inhibitory peptide that inhibits gastric motility and the enterogastric reflex that stimulates gastric motility.

The blood surrounding the stomach would have a pH slightly higher than blood in other parts of the body.

The process of emptying the stomach takes about 12 hours after a meal.

Glycogen and sucrose are examples of polysaccharides.

The formation of feces is the primary function of the rectum.

Ingestion,digestion,secretion,and absorption are all necessary for the proper functioning of the digestive system.

Vitamins A,D,E,and K depend on bile salts for their absorption.

Lactose and maltose are examples of disaccharides.

The sodium cotransport,which carries both sodium ions and glucose molecules,is an active transport mechanism.

Although both peristalsis and segmentation require movement of the alimentary canal,only peristalsis moves food through the alimentary canal.

Contact digestion makes absorption more efficient because the end products are then physically near the point of absorption,not floating around somewhere in the lumen.

Peristalsis is a back-and-forth action that breaks apart chunks of food and mixes in digestive juices.

The enterogastric reflex stimulates gastric motility as food enters the duodenum.

Blood in the hepatic portal system is much more likely to reflect the amount of glucose and amino acid absorbed than is the blood in the inferior vena cava.

One important role of the salivary glands is the production of mucus,because they are the only glands that produce it.

The three stages of deglutition are the oral stage,the laryngeal stage,and the esophageal stage.