The Digestive System

1. The Digestive System 7th Grade Life Science

2. Major Functions of the Digestive System • Break down ingested food • Put nutrients into the bloodstream • Remove waste from the body

3. Organs of the Digestive System • Mouth- teeth, salivary glands, tongue • Esophagus • Stomach • Small Intestine • Large Intestine • Pancreas • Liver • Gall bladder Accessory Organs

4. Mouth • Digestion begins here! • Teeth and tongue are used in mechanical digestion- physical breakdown of food • Saliva and enzymes begin chemical digestion- chemical breakdown of food

5. Esophagus • Muscular tube that connects mouth to stomach • Moves food downward by peristalsis, or muscular contractions • Epiglottis seals off windpipe during swallowing to prevent choking

6. Stomach- Mechanical and Chemical Digestion • Muscular pouch that expands to hold your food • Hydrochloric acid (HCl) and the enzyme pepsin combine to form gastric juice • A gummy coating of mucus protects the stomach lining from the strong chemicals • Chyme, a thick liquid containing partially digested food, is produced here

7. Small Intestine • Most chemical digestion occurs here! • Inner surface is covered in villiand microvilli, millions of tiny finger-like projections that absorb nutrient molecules from the chyme • The villicreate a large surface area so as many nutrients as possible can be a absorbed • Longest portion of the digestive tract

8. Liver • Makes bile to break up fat • Storesnutrients • Breaks down toxins

9. Gallbladder • Temporarily stores bile and releases it into the small intestines

10. Pancreas • Makes digestiveenzymes • Makes hormones that regulate sugar levels

11. Large Intestine • No digestion occurs here • Water is absorbed from remaining food • Bacteria feed on material passing through and produce Vitamins (K)vital to our health • Waste material, feces, is prepared for elimination from the body

12. Rectum • Stores feces until they can be expelled through the anus.

13. The End!