DIGESTION

*DIGESTION: process that breaks down large molecules into smaller, more usable molecules. A. MOUTH: 1. Place where food enters the body. 2. Food is physically broken down by the teeth.

3. SALIVA: chemically breaks down food a. Three pairs of salivary glands produce saliva b. Saliva contains amylase which starts to breakdown starch into maltose. c. Provides moisture to aid in transport through the digestive system.

B. ESOPHAGUS 1. Carries food from the mouth to the stomach. 2. Food is moved by peristalsis: alternating contraction and relaxation of muscles.

C. STOMACH 1. Main function: to store food. 2. The muscular wall of the stomach also churns the food. (This is a physical movement- grinding of the food).

3. Stomach chemically breaks down food w/ use of pepsin and HCl 3. Stomach chemically breaks down food w/ use of pepsin and HCl. These break down proteins into smaller polypeptides. 4. The mixture of food and acidic liquid is called chyme. 5. Stomach lining is protected by a fine mucus. 6. There is a sphincter at both ends of the stomach to keep mixture in until it’s time to be digested.

D. SMALL INTESTINE 1. Longest part of the digestive tract: seven meters long(twenty-one feet) 2. Function: most digestion is done here & nutrients are absorbed. 3. Fluids from the pancreas and liver are added to the chyme from the stomach.

4. Nutrients are absorbed by the body through villi. 5. Villi: small fingerlike projections that contain many blood vessels. *Also  the amount of surface area for absorption.

E. HELPER ORGANS 1. LIVER produces bile. Bile breaks down fats. 2. GALLBLADDER stores bile and releases it into the small intestine. LIVER Gallbladder

3. PANCREAS Insulin breaks down sugar. Glucagon breaks down starches. Protease breaks down protein. Peptidases break down polypeptides. Sure, I have permission!

F. LARGE INTESTINE 1. Main function: to absorb water from digested material. 2. Bacteria have a mutualistic relationship with humans. Humans provide them with food and they provide vitamins, amino acids, and some protection from harmful bacteria.

THE END G. RECTUM & ANUS 1. Undigested food is stored in rectum 2. Eliminated through the anus THE END