THE DIGESTIVE SYSTEM

ON YOUR DIAGRAM a) label the parts of the digestive system ​that you know, then use your textbook (Chp. 35) to help you out. b)We will review the labelling c) Use your textbook to complete the ​Function of the parts you have identified on the hand-out provided

THE DIGESTIVE SYSTEM Composed of two main portions: The Alimentary Canal Through which materials for digestion move Accessory Organs From which secretions, enzymes and juices aid the digestive process

4 MAIN PARTS OF THE DIGESTIVE SYSTEM 1) Ingestion: the taking IN of nutrients 2) Digestion: the breakdown of organic molecules into ​smaller compounds a) Mechanical Digestion -the physical breakdown of food (chewing, ​grinding, peristalsis [stomach action or ​churning]) b) Chemical Digestion -the breakdown of the complex molecules ​into simple ones by the action of enzymes

4 MAIN PARTS OF THE DIGESTIVE SYSTEM 3) Absorption: the transport of digested nutrients to the ​tissues of the body 4) Egestion: the removal of materials from the body that cannot be digested Trip Through the Digestive System

STRUCTURE & FUNCTIONS 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

STRUCTURE & FUNCTIONS Salivary Glands Function: to produce saliva in response to smell, feel, taste or thought of food Saliva contains SALIVARY AMYLASE, which begins to break down starches   Epiglottis Function: a flap of tissue that covers the wind pipe (trachea) when swallowing

STRUCTURE & FUNCTIONS Esophagus Function: A muscular tube that moves food from the pharynx to the stomach uses muscle action called peristalsis. Note: Peristalsis is the wave like motion of muscular tissue that pushes substances through out digestive system! Pharynx Function: the part we call our throat, connection the mouth and esophagus

STRUCTURE & FUNCTIONS 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 1) Cardiac sphincter: prevents the regurgitation of the stomach contents back into the esophagus. 2) Pyloric sphincter: located at the end of the pyloric canal of the stomach, and controls gastric secretions. 3) Ileocecal sphincter: located at the end of the small intestine, and prevents the contents of the small intestine from entering the large intestine.

STRUCTURE & FUNCTIONS 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   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

STRUCTURE & FUNCTIONS How the Small Intestine Works 1. Duodenum The first part of the small intestine The main role is to complete the 1st phase of digestion 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 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.

STRUCTURE & FUNCTIONS 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

STRUCTURE & FUNCTIONS 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 Storage for good “gut” bacteria Liver 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

STRUCTURE & FUNCTIONS Pancreas Function: to produce digestive juices that help to reduce the acidity of gastric juice from stomach To produce: Insulin (hormone) which controls sugar levels in the blood Amylase – breaks down starch Trypsin – Breaks down proteins Lipase – breaks down fat 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