THE DIGESTIVE SYSTEM

Transcription

1 THE DIGESTIVE SYSTEM Composed of two parts: There are 4 main parts of digestion: 1. Ingestion: 2. Digestion: a. Mechanical Digestion: Example: b. Chemical Digestion: Example: 3. Absorption: 4. Egestion: PARTS OF THE DIGESTIVE SYSTEM Tongue Function: To taste food Shapes food into a ball called a bolus Push food to the back of the mouth into the pharynx Teeth Function: to cut, tear, smash and grind food into small pieces and form a paste Salivary Glands Function: to produce saliva in response to smell, feel, taste or thought of food Saliva contains AMYLASE, which begins to break down starches Sketch: Epiglottis Function: a flap of tissue that covers the wind pipe (trachea) when swallowing Esophagus Function: A muscular tube that moves food from the pharynx to the stomach Uses muscle action called peristalsis Note: Pharynx Function: the part we call our throat, connection the mouth and esophagus Sphincters Function: a ring of muscle that separates the stomach from the small intestine. Opens and closes to control the movement of food into intestines Acts like a purse strong that can open and close 3 Sphincters in Digestive System Stomach Function: stores food and releases it slowly into small intestine Helps break down food (mechanical digestion) Produces gastric juices that help digest food Product leaving the stomach is called Chyme

2 Small Intestine Function: digests food into small molecules and to absorb the molecules into the bloodstream Is about 20 feet long Is the place where most absorption occurs Villi line the small int. & function absorb nutrients How the Small Intestine Works 1. Duodenum The first part of the small intestine The main role is to complete the 1 st phase of digestion o Food from the stomach is mixed with enzymes from the pancreas and bile from the gallbladder. The enzymes and the bile help to break down food into smaller molecules 2. Jejunum The second part of the small intestine The inside walls absorb the food nutrients o Have circular folds called villi, which increase SA to absorb nutrients 3. Ileum The third part of the small intestine Its absorbs bile acids, which are returned to the liver to be made into more bile, then stored in the gallbladder for future use Also absorbs vitamin B, which the body uses to make nerve cells and red blood cells. Large Intestine (Colon) Function: to absorb remaining water from food waste Semi-solid feces are formed About 5 feet long Some complex carbohydrates are digested here Rectum Function: Stores feces until they can be eliminated Final 6 inches of large intestine Can expand Anus Function: where feces and body waste leave the body Appendix Function: extension of first part of large intestine Leftovers of digestion flow through here Helps in the body s defense against disease, but we don t need it to be healthy o Storage for good gut bacteria Sketch: Liver

3 Function: to produce bile (a chemical that helps to digest fats) Regulates blood glucose levels Converts toxic ammonia into urea and detoxifies harmful substances we ingest Stores fats and carbohydrates for energy Gall Bladder Function: to store and concentrate the bile produced in the liver Releases bile and bile salts into small intestine through the bile duct Note: If proteins & fats are detected in the intestine, the GB is stimulates to release stored bile Pancreas Function: to produce digestive juices that help to reduce the acidity of gastric juice from stomach To produce: o Insulin (hormone) which controls sugar levels in the blood o Amylase breaks down starch o Trypsin Breaks down proteins o Lipase breaks down fat o Sodium bicarbonate helps neutralize stomach acid (basic) Uvula Function: to cover the breathing passage between your nose and mouth when you swallow Helps change the sound of your voice

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