2. Lesson 6 Digestive System

3. AIM : How does the digestive system work to maintain a stable and healthy body? Do Now: What are you doing?

4. What is the Digestive System? Digestion – the process that breaks down food into forms that the body can use. Digestive system- organs that break down food into molecules. Food provides proteins and nutrients the body needs.

5. 3 Functions of the Digestive System 1. It breaks down food into molecules the body uses. 2. The molecules are absorbed into the blood stream and carried through to the body. 3. Wastes are eliminated from the body.

6. Parts of the Digestive system Esophagus Stomach Small Intestine Large Intestine Liver Gall Bladder Pancreas

7. 2 types of Digestion There are two ways that digestion takes place. 1. Mechanical Digestion 2. Chemical Digestion Together these two processes change food to atoms and molecules.

8. Mechanical Digestion Is a physical change that results in breaking up food into smaller pieces. Done by the mouth and teeth.  Chewing  Mixing  Biting  Tearing

9. Chemical Digestion Chemicals break down large molecules into smaller parts. Is a chemical change that breaks down your food. Ex: saliva, acid in the stomach and small intestine. Video: 5:35-8 Enzyme- a protein that produces chemical reactions

10. Check For Understanding Which statement about digestion is true? A. Saliva digests food mechanically; teeth digest it chemically. B. Mechanical digestion and chemical digestion occur in the large intestine. C. Enzymes digest food chemically; teeth digest food mechanically. D. Chemical digestion mashes up food; mechanical digestion breaks it up with enzymes.

11. Do Now AIM: What is the difference between mechanical and chemical digestion? Write heading and AIM in notebook. As soon as you are completely quiet, I will distribute something….

12. Digestion in the mouth 1. Put half the cracker in your mouth and chew. In your notebooks, record what it tastes like. Sweet? Plain? Hard? Soft? Salty? (bullets are fine.)

13. 2. When I say to begin, you will put the second half of the cracker in your mouth, but you WILL NOT chew it. You will keep it in your mouth for 1.5 minutes. When I give you the signal, think about the following questions: A. What does it feel like at first? B: after 1 minute? C. After 1.5 minutes? D. When you chew it?

14. Human Digestion http://www.discovery.com/tv-shows/other- shows/videos/assignment-discovery-shorts-06-07-07- 08-human-digestion.htm http://www.discovery.com/tv-shows/other- shows/videos/assignment-discovery-shorts-06-07-07- 08-human-digestion.htm

15. The Steps of Digestion 1. Mouth Where food enters the digestive system.  In the mouth food is chewed up  Teeth bite the food and chew it before it moves on to the tongue  The tongue moves the food around mixing it with saliva.

16. Saliva  Is a secretion that contains an enzyme important for breaking down food.  Within the mouth both mechanical and chemical digestion occur.

17. 2. Esophagus  A muscular tube that connects the throat to the stomach  Is about 10 inches long  It takes about 4-10 seconds for food to move down your esophagus.  No digestion takes place here.

18. Esophagus continued  The walls of the esophagus are layered with muscles that squeeze and push food along in process called “Peristalsis”  Food travels through the esophagus towards the stomach.

19. 3. Stomach  the stomach is a muscular bag like organ that can shrink and stretch.  Food is temporarily stored here

20. Stomach continued Both chemical and mechanical digestion Mechanical: The muscles of the stomach contract mixing all of the food inside it together Chemical: food is mixed with enzymes and strong digestive juices like hydrochloric acid to break it down

21. Stomach continued Stomach also produces mucus which protects the wall from the strong digestive juices. Food moves through your stomach in 2-4 hours. Turns partially digested food into a watery substance- Chyme

22. AIM : How does the digestive system get nutrients to our cells? (How does a turkey sandwich give us energy?) Do Now: Write heading and AIM. In notebooks, write down some possible answers to the AIM question.

23. 4. Small Intestine About 22 feet long!!! Finishes chemical digestion of food. Absorbs nutrients and sends them to the bloodstream Villi – finger-like structures covering inner wall, allow for absorption of nutrients

24. Small Intestine: Part 1: Duodenum First part of the small intestine which is connected to the stomach. Most digestion takes place here Bile from the liver is added to help break down particles.

25. 5. Large Intestine About 5 Feet long Absorbs what the small intestine does not absorb Takes undigested food and turns it into waste. LI keeps water in your body to maintain homeostasis. Video 8:50-11 You can lose a large part of your large intestine and still survive

26. Check For Understanding Which is a function of the large intestine? A. It absorbs nutrients from food and puts them into the bloodstream B. It takes nutrients to all the cells of your body C. It breaks down food chemically D. It absorbs extra liquid from food your body could not digest

27. Liver Affects digestion by producing bile Bile- Helps digest fat Processes nutrients in the blood, filters out toxins and waste. Is often called the body’s energy factory. You cannot live without a liver, although you can live with a part of one. Drinking alcohol damages the liver.

28. Gall Bladder Stores bile from the liver. Delivers bile when food is digested. Fatty diets can cause gallstones. You can live without a gallbladder.

29. Pancreas Produces digestive juices for further break down food. Regulates blood sugar by producing insulin. (homeostasis)** If it does not work you get diabetes.

30. Bacteria Many types of bacteria live in your body and organs Some are good for you Bacteria in the digestive system make vitamins you need.-Vitamin K and two B vitamins. Vitamin K- blood clotting Vitamin B-helps nervous system.