Transcript Digestion
Digestive System 1 Function: • Break down food into small molecules so it can be absorbed and moved by the blood which delivers it to your cells for energy. 2 Types of digestion 2 types of digestion • Mechanical: food is cut, mixed, or churned into smaller pieces. 2 types of digestion • Chemical: saliva, bile, and acid help break down or dissolve the chemical bonds of the food molecules The Path of Food 1. Ingestion (eating) 2. Digestion (breaking down food molecules) 3. Absorption (by cells) 4. Elimination (disposal of unused food) Organs of the Digestive System 1. Food is chewed in the mouth • • Mechanical-chewing and ripping it into smaller pieces Chemical-saliva starts to dissolve starches http://www.youtube.com/watch?v=CsYbO6zBR74 2. Slimy pieces of food slide down the pharynx, past the epiglottis, into the esophagus http://www.youtube.com/watch?v=QvGYvK6qScE&feature=related 3. Food is squeezed down the esophagus by muscle contractions called peristalsis. 4. Food lands in the stomach • Mechanical digestion-food is churned and mixed • Chemical digestion-food is mixed with enzymes and acids to break it down. http://www.youtube.com/watch?v=cp-SEs6dxR8&feature=related heartburn video 5. 2-4 hours later, food is now a watery liquid and it slowly moves into your small intestine. Stomach Stapling This reduces the Stomach size ofsize theis reducedand andsmall stomach intestinal is intestine,length thereby shorted to reduce restricting food theintake amount food andofcaloric storedabsorption. and calories absorbed. Small Intestine 6. In the small intestine food is digested even more and then absorbed by the bloodstream. 7. Fat is chemically digested in the small intestine by bile. The liver makes bile and extra bile is stored in the gall bladder • Carbohydrates, proteins, and fats are also chemically digested by a digestive solution made by the pancreas. 8. Millions of villi in the small intestine allow the blood to pick up the nutrients (absorb) to deliver to cells around the body. http://www.youtube.com/watch?v=xu5jDCX2cHM http://www.youtube.com/watch?v=_GTQBiZni6w 9. Remaining food and liquid is moved into your large intestine by peristalsis. 10. Water is absorbed from the large intestine back into the body. http://www.youtube.com/watch?v=PpzfKt-47iA&feature=related 11. Remaining food is compacted and released from the body as feces through the rectum and anus. The End! 1. Mouth 2. Salivary Glands 3. Gall Bladder 4. Liver 5. Pancreas 6. Small Intestine 7. Esophagus 8. Stomach 9. Large Intestine 10. Rectum 11. Anus Review of digestion 1. Draw a plate of food 2. Food goes into the mouth a. Mechanical digestion by teeth (tear dinner in half) b. Chemical digestion by saliva (tear dinner in half again) 3. Food moves into the esophagus No digestion occurs 4. Into the stomach a. Mechanical digestion churning muscles (tear pieces in half) b. Chemical digestion by acid (tear pieces in half again) 5. Into the small intestine a. Chemical digestion by bile (tear pieces in half again) b. Absorption by blood stream (I will come around and collect some nutrients) 6. Into the large intestine a. Absorption of water by blood stream (I will come around and collect some water) 7. Elimination of unused food a. Form compact feces from remaining food particles (I will come around and collect the feces)