N105: Essentials of Nursing Care - Health Differences

Essentials of Nursing Study Guide

©2017 Achieve Test Prep Page 7 of 160 Gastric juice in the stomach starts proteindigestion. Gastric juice mainly contains hydrochloric acid and pepsin. As these two chemicals may damage the stomach wall, mucus is secreted by the stomach, providing a slimy layer that acts as a shield against the damaging effects of the chemicals. At the same time protein digestion is occurring, mechanical mixing occurs by peristalses, which are waves of muscular contractions that move along the stomach wall. This allows the mass of food to further mix with the digestive enzymes. After some time, typically an hour or two in humans, the resulting thick liquid is called chyme . When the pyloric sphincter opens, chyme enters the duodenum where it mixes with digestive enzymes from the pancreas, and then passes through the small intestine, in which digestion continues. When the chyme is fully digested, it is absorbed into the blood. Chapter One: Nutrition Nutrition is all the processes involved in consuming and utilizing food for energy, maintenance, and growth. 1.1 Physiology of Nutrition There are five processes involved in the body’s use of nutrients: Ingestion, Digestion, Absorption, Metabolism and Elimination. Process #1 Ingestion is the taking of food into the digestive tract, generally through the mouth. In other words, it is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, usually through eating or drinking. Besides nutritional items, other substances which may be ingested are medications (where ingestion is termed oral administration). Process #2 Digestion is the mechanical and chemical processes that convert nutrients into a physically absorbable state. Digestion includes mastication (chewing), deglutition (swallowing), and peristalsis (coordinated, rhythmic, serial contractions of the smooth muscles of the GI tract). In other words, it is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream. Digestion is a form of catabolism , which is a breakdown of large food molecules to smaller ones. When food enters the mouth, digestion starts by the action of mastication (chewing), which is a form of mechanical digestion, and the contact of saliva. Saliva, which is secreted by the salivary glands, contains saliva y amylase , an enzyme which starts the digestion of starch in the food. After undergoing mastication and starch digestion, the food will be in the form of a small, round slurry mass called a bolus . It will then travel down the esophagus and into the stomach by the action of peristalsis .