The Digestive System

A. Function of the digestive system Physical breakdown of food a. Mastication – chewing food using teeth Chemical breakdown of food a. Salivary Enzymes – breakdown starches into smaller molecules, occurs in the mouth b. Gastric Acid – breakdown of food in the stomach

Steps in Digestion Mouth – Crushing and grinding, saliva Esophagus - a long tube that runs from the mouth to the stomach. It uses rhythmic, wave-like muscle movements to force food from the throat into the stomach. This muscle movement gives us the ability to eat or drink even when we're upside-down Stomach – gastic juices, include hydrochloric acid. Food sits in the stomach for 1-4 hours

Starch Digestion Amylase – enzyme found in saliva Maltase – enzyme found in the small intestine breaks the starch into molecules called maltose splits the maltose into glucose molecules that can be absorbed into the blood. Glucose is carried through the bloodstream to the liver, where it is stored or used to provide energy for the body

Steps in Digestion Cont. Small Intestine – bile (produced in the liver and stored in the gall bladder), pancreatic enzymes, and other digestive enzymes produced by the inner wall of the small intestine help in the breakdown of food (Total of 20 feet long!!!) Digested food is absorbed into the blood stream. Large Intestine - some of the water and electrolytes (chemicals like sodium) are removed from the food. Many bacteria like Bacteroides, Lactobacillus acidophilus, and Escherichia coli in the large intestine help in the digestion process.

Steps in Digestion Cont. Colon - connects to rectum- anal canal opens to the anus. Fecal material (solid waste) is expelled.

Liver, gall bladder and pancreas Liver - largest gland in your body 1. Secretes bile - softens fat, makes them water soluble. 2. Stores glucose in the form of glycogen 3. Detoxifies blood Gall bladder- stores bile Pancreas- produces insulin, makes enzymes amylase and lipase. Insulin regulates the uptake of glucose by the cells

Salivary Gland Teeth Tongue Epiglottis Esophagus Liver Stomach Gall Bladder Bile Duct Duodenum Pancreas Transverse Colon Ascending Colon Small Intestine Descending colon Appendix Rectum

The first step in digestion of a fat is to dissolve it into the watery content of the intestine. The bile acids produced by the liver helps dissolve fat in water and allow the enzymes to break the large fat molecules into smaller molecules, some of which are fatty acids and cholesterol. small vessels carry the fat to the veins of the chest, and the blood carries the fat to storage in different parts of the body. Fats

Protein  AMINO ACIDS Consist of giant molecules of protein that must be digested by enzymes before they can be used to build and repair body tissues. An enzyme in the stomach starts the digestion of swallowed protein. Further digestion is completed in the small intestine. The breakdown of huge protein molecules into small molecules called amino acids. Carried into the blood stream Meats, eggs, beans