- breaks down food into molecules the body can use, getting rid of undigested molecules htm htm Digestive System

peristalsis – muscle contractions, moves food through tract sphincters - valves; regulate passage of material between chambers

The Digestive Tract Gastrointestinal Tract (GI) Mouth – Teeth – physical saliva – moistens and lubricates food - amylase – begins the breakdown of carbohydrates (chemical) Pharynx –back of throat –food (bolus) triggers reflex –epiglottis – flap of cartilage, covers trachea

Esophagus – connect mouth to stomach

Stomach – * physical and chemical digestion *gastric juice secreted by cells of stomach hydrochloric acid (HCl)– unfolds the proteins (exposing the bonds to be broken later) pepsin – enzymes breaks down proteins into polypeptides; Works in the acidic envioronment *peristalsis

Small intestines completes digestion absorption of nutrients *duodenum – 1 st part of small intestines; receives secretions from pancreas, liver and gallbladder bile – produced by liver and stored in gallbladder - breaks down fats enzymes complete digestion of carbs, proteins and lipids lipase – further breaks down fats

Trypsin – produced by the pancrease, Breaking down polypeptides into amino acids amylase –Pancreatic amylase further breaks down carbs

Absorbtion of nutrients to the blood villi – fingerlike projections; cover lining of small intestines. -increase surface area for absorption

Large intestines - colon water absorption compacting undigested material – waste (feces) Rectum storage and elimination of waste

Digestive System also includes the liver and the pancreas –Pancreas Produces digestive enzymes insulin –Liver Digested molecules absorbed into bloodstream transported to liver Maintains blood sugar levels

Liver Nutrients transported to the liver Stores extra sugar as glycogen converts glycogen back to glucose to use for energy Modify amino acids –Ex: make amino acids and proteins Detoxifies poison –Stores poisons unable to change

Cirrhosis – scarring of the liver

Ex: