1. Digestive System

2. What does the Digestive System Do? Function: To break down food, absorb nutrients, and get rid of solid food and waste 2 types of digestion: 1.Mechanical digestion- large chunks of food are broken down into small pieces and is a physical process 2.Chemical digestion- large food molecules are broken down into small nutrient molecules and is a chemical process Absorption: Process that allows substances you eat to be taken up by the blood

3. Role of Enzymes in Digestion Enzyme- protein that speeds up chemical reactions in the body Digestive Enzyme Where it is produced What it breaks down AmylaseMouthStarches PepsinStomachProteins into amino acids TrypsinPancreasProteins Pancreatic lipasePancreasFats BileLiverFats

4. Pathway of food through the Digestive System 1. Mouth Chemical digestion (amylase) When you start eating, salvia wets the food and makes it easier to break up and swallow Mechanical digestion Teeth aid is tearing and grinding food into smaller pieces and your tongue will push the mixture back 2. Esophagus Narrow tube that carries food from the throat to the stomach Epiglottis: flap of cartilage located in the throat behind the tongue and in front of the larynx, at rest it allows air to pass into the larynx and lungs, when a person swallows it folds backward to cover the entrance of the larynx so food and liquid do not enter the windpipe and lungs Mechanical Digestion Is able to move food because of peristalsis (wave-like muscles contractions)

5. Pathway of food through the Digestive System 3. Stomach Chemical digestion Food is mixed around in HCl with the enzyme pepsin and as a result is turned into chyme Mechanical digestion Muscles contract and relax moving food around and breaking it into smaller pieces Water, salts, and simple sugars are absorbed into the blood from the stomach while the remaining is stored in the stomach until the small intestine is ready 4. Small intestine 23 feet long and is made up of 3 parts: 1.duodenum-is the 1 st part, is where most chemical digestion takes place, and is where enzymes are secreted 2.jejunum-2 nd part, most nutrients are absorbed into the blood and is lined with tiny “fingers” called villi, which increase the surface area for more absorption 3.ileum-3 rd part, covered in villi and the few remaining nutrients are absorbed here (longest section)

6. Digestive Organs and Their Roles 5. Large intestine 5 feet long made up of the cecum, colon, and rectum (shorter length wise but WIDER in diameter than the small intestine) Waste enters and is moved along the large intestine so excess water is absorbed 6. Anus Muscles contract and relax to let feces out of the body called stool

7. Other Organs *These organs do NOT have food pass through them! Liver- breaks down toxins and makes bile (brownish-yellow fluid that breaks down fat) Gall bladder-stores bile and delivers it to the small intestine Pancreas- produces pancreatic juices that neutralizes stomach acid; regulates insulin levels aka sugar levels Appendix- attached to the cecum; a vestigial organ meaning it once had a function but no longer does; is thought to have helped digest cellulose found in plants and store good bacteria