Chapter 14- The Digestive System

ingestion

Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in the substance through the mouth into the gastrointestinal tract, such as through eating or drinking.

mastication

Mastication or chewing is the process by which food is crushed and ground by teeth. It is the first step of digestion, and it increases the surface area of foods to allow more efficient break down by enzymes. During the mastication process, the food is positioned by the cheek and tongue between the teeth for grinding.

mechanical digestion

There are two kinds of digestion: mechanical and chemical. Mechanical digestion involves physically breaking the food into smaller pieces. Mechanical digestion begins in the mouth as the food is chewed. Chemical digestion involves breaking down the food into simpler nutrients that can be used by the cells.

bile

a bitter greenish-brown alkaline fluid that aids digestion and is secreted by the liver and stored in the gallbladder.

mesentery

a fold of the peritoneum that attaches the stomach, small intestine, pancreas, spleen, and other organs to the posterior wall of the abdomen.

emulsification

emulsification (in digestion) The breakdown of fat globules in the duodenum into tiny droplets, which provides a larger surface area on which the enzyme pancreatic lipase can act to digest the fats into fatty acids and glycerol. Emulsification is assisted by the action of the bile salts (see bile).

deglutition

the action or process of swallowing.

hydrolysis

the chemical breakdown of a compound due to reaction with water.

absorption

the process or action by which one thing absorbs or is absorbed by another.

feces

waste matter discharged from the bowels after food has been digested; excrement.

peristalsis

the involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wavelike movements that push the contents of the canal forward.

chemical digestion

the process in the alimentary canal by which food is broken up physically, as by the action of the teeth, and chemically, as by the action of enzymes, and converted into a substance suitable for absorption and assimilation into the body. 2. the function or power of digesting food: My digestion is bad. 3.

chyme

the pulpy acidic fluid that passes from the stomach to the small intestine, consisting of gastric juices and partly digested food.