Purpose of the Digestive System - the break down of food into nutrients digestion: process that breaks down food into small molecules so that they can be absorbed and moved into the blood -the blood transports the nutrients to all parts of the body so it can be used to make energy - unused molecules pass out of your body as wastes

Types of Digestion mechanical digestion: the breaking, crushing and mashing of food - starts in the mouth when food is chewed - continues in the stomach when food is mixed and churned chemical digestion: large molecules are broken down into nutrients using chemicals called enzymes - starts in the mouth with saliva mixing with food - continues in the stomach with acids - finishes in the small intestine

Digestive Tract - mouth: teeth chew (mechanical digestion) and the tongue pushes food around - saliva breaks down food (chemical digestion) - esophagus: muscular organ uses peristalsis: wavelike movement to squeeze food to stomach - stomach: muscular baglike organ that continues mechanical and chemical digestion - creates a soupy mixture called chyme - small intestine: chemical digestion is finished here; food has been broken down into nutrients, which are absorbed into the blood - large intestine: main job is to absorb water from undigested food mass - undigested materials become solid waste (feces), which is stored in the rectum and is expelled through the anus

liver: makes a green liquid called bile, which is used to digest fat gallbladder: stores bile produced by the liver pancreas: makes materials that neutralize the acid in chyme and further chemically breakdown proteins Additional Digestive Organs Liver

Digestive Diseases Heartburn: results from backflow of chyme from the stomach into the esophagus, which causes a burning sensation in the chest or throat Gastric Ulcer: an open sore on the stomach lining caused by bacteria Colon Cancer: affects part of the large intestine and is caused by cells dividing uncontrollably to form a tumor Constipation: body does not get enough fiber, water or exercise so the feces become dry, which makes it hard to get rid of the solid waste Diarrhea: indigestible food moves too quickly through the large intestine, so water is not removed and solid waste becomes a liquid