THE DIGESTIVE SYSTEM TEACHER COPY

Transcription

1 THE DIGESTIVE SYSTEM TEACHER COPY

2 THE DIGESTIVE SYSTEM There are three primary functions for the digestive system 1. Break down food into molecules the body can use 2. The molecules are absorbed into the blood and carried throughout the body 3. Wastes are eliminated from the body

3 THE DIGESTIVE SYSTEM How do you digest food? Digestion- the process by which your body breaks down food into small nutrient molecules. There are two kinds of digestion Mechanical Digestion- when you bite and chew food Chemical Digestion chemicals produced by the body break foods into smaller chemical building blocks Absorption- is the process by which nutrient molecules pass through the wall of your digestive system into your blood

4 THE DIGESTIVE JOURNEY The mouth- both mechanical and chemical digestion begin in the mouth. Mechanical digestion in the mouth is performed by your Teeth Chemical digestion in the mouth is performed by your. Saliva Saliva is an enzyme which are proteins that speed up chemical reactions in the body.

5 THE DIGESTIVE JOURNEY As you swallow a flap of tissue called the epiglottis closes off your windpipe, preventing food from entering. The food then enters the esophagus which is a muscular tube that connects the mouth to the stomach. Food remains in the esophagus for only about 10 seconds. After food enters the esophagus, contractions of smooth muscle push the food toward the stomach. This muscle contraction is called peristalsis

6 THE DIGESTIVE JOURNEY After food leaves the esophagus, it enters the stomach There is mechanical and chemical digestion in the stomach Mechanical digestionthe smooth muscle in the stomach contracts to produce a churning motion and mixes the food with fluids Chemical digestion- The stomach contains digestive juice that contains the enzyme pepsin and hydrochloric acid

7 FINAL DIGESTION AND ABSORPTION After the liquid leaves the stomach it enters the small intestine where most chemical digestion takes place. Almost all chemical digestion and absorption of nutrients takes place in the small intestine and the nutrients from food will eventually enter the bloodstream. This is completed with the help from the liver, gallbladder and pancreas. Dr Bionics Digestive System

8 THE LIVER The liver breaks down medicines, eliminates nitrogen from the body and produces bile. Bile breaks up fat particles. It flows from the liver into the gallbladder where the bile is stored. After eating the stored bile passes through a tube from the gallbladder and into the small intestine. Bile breaks up large fat particles into smaller fat droplets.

9 THE PANCREAS The pancreas produces enzymes that flow into the small intestine and help break down starches, proteins and fats. Together the bile from the liver and the enzymes from the pancreas help to complete chemical digestion while food travels through the small intestine.

10 ABSORPTION IN SMALL INTESTINE After chemical digestion occurs the small nutrient molecules are absorbed by the villi in the small intestine. Villi are tiny finger like structures that line the small intestine and absorb nutrient molecules. Blood vessels run through the center of each villus and nutrient molecules can pass from the cells on the surface of a villus into blood vessels. The blood carries the nutrients throughout the body for use by body cells.

11 THE LARGE INTESTINE Once the liquid food material reaches the end of the small intestine most of the nutrients have been absorbed. The remaining material moves into the large intestine The water from the food material is absorbed into the bloodstream and the remaining material is readied for elimination from the body. The large intestine ends at the rectum where waste material is compressed into solid form and is then eliminated from the body through the anus.

12 PUT THE DIGESTIVE SYSTEM TERMS IN ORDER Esophagus Mouth Small intestine Large intestine Stomach Bloodstream