1. The Digestive System

2. Overall Functions of Digestive System 1.Taking in Food 2.Breaking Down Food 3.Absorbing Food 4.Eliminating Wastes

3. Salivary glands Esophagus Liver Stomach Gall Bladder Pancreas Large Intestine Small Intestine Rectum Anus

4. The Digestive Tract One long tube with two openings In humans, tube consists of: Mouth Esophagus Stomach Small intestine Large intestine Anus Accessory Organs: Liver Gall Bladder Pancreas

5. The Digestive Tract Tissues: Entire tract is lined with epithelial tissues (different types of cells) One type of cell is called a Goblet Cell  cells that secrete mucus Mucus protects digestive tract from digestive enzyme Mucus allows materials to pass smoothly along digestive tract Facilitate Diffusion Tract also includes layers of muscle, connective tissue and nerve tissue

6. Taking in Food

7. Breaking Down Food

8. The Mouth Begins the breakdown of food in two ways: Mechanically (teeth and tongue) and Chemically (with the use of enzymes) Salivary glands secrete saliva: A mixture of water and enzymes Enzymes start chemically breaking down food, making it soft enough to pass down into the esophagus

9. What is an Enzyme ? Acts as a Catalyst to speed up the reaction. Secreted Enzymes Break Down PROTEINS into its SMALLER components so that they can be used by your body

10. Why do we chew our food ? SURFACE AERA The larger the surface area is the greater chance a molecule of food will run into an enzyme or HCL molecule THIS WILL INCREASE THE RATE OF DIGESTION

11. The Esophagus Muscular tube that connects the mouth to the stomach Muscles are a special type called smooth muscle tissue – contract and relax without conscious effort Movement is controlled by nerve tissue Esophagus moves food down esophagus through the movement of the smooth muscle tissue via a process called peristalsis NO DIGESTION OCCURS HERE

12. The Stomach Mechanical and Chemical Digestion occur here Mechanical – stomach churns and moves food around, breaking it down into smaller pieces (controlled by smooth muscle tissue) Chemical – stomach lining cells secrete enzymes and hydrochloric acid which chemically break down food Stomach is supplied with nerve cells that signal when it is ‘full’

13. Stomach Cell Specialization Goblet Mucous Cells – Secrete a BASIC mucus that protects the lining of the stomach Parietal Cells- Secrete HCL or Hydrochloric Acid Chief Cells – Secrete Enzymes that Break down proteins Why isn’t the stomach harmed by the extremely acidic HCl in the stomach?

14. Absorbing Food

15. The Intestines Lining has goblet cells that produce mucus Contains capillaries (small blood vessels) that connect the digestive system to the circulatory system Contains smooth muscles that contract and relax without conscious thought Perform peristalsis

16. The Intestines The Small Intestine 6m long and narrow Most digestion occurs here Nutrients diffuse from small intestines into the bloodstream Inner layer contains villi and microvilli which function to increase the surface area of the intestines for maximum nutrient absorption

18. Closer Look

19. Eliminating Wastes

20. The Intestines Large Intestine aka the colon 1.5m long, and wider than sm. Intestine Lining absorbs water from indigestible food Remaining solid matter is excreted as feces from the anus

21. Accessory Organs Liver Secretes enzymes for digestion Produces bile, which helps breakdown fats Gall Bladder Stores bile Pancreas Secretes enzymes for digestion

22. Salivary glands Esophagus Liver Stomach Gall Bladder Pancreas Large Intestine Small Intestine Rectum Anus