1. Digestive System

2. Getting Ready Activity Materials: (per pair) 1 piece of paper 1 pen Instructions: Going back and forth between you and your partner, try to map the journey that food takes as it goes through the digestive system Be as detailed as possible (try to mention at least 8 organs) You have one minute to complete the activity

3. Language Connection The digestive tract is often called the ‘gastrointestinal’ tract, or GI tract for short Gastro (greek) = stomach Intestinal = intestines Gastric – of or relating to the stomach Gastronomy – study of the culture of food Gastric bypass – surgery that bypasses the stomach Gastroenteritis – inflammation (infection) of the stomach

4. Digestive System The organ system that is made up of the mouth, esophagus, stomach, intestines, liver, pancreas, and gall bladder The system that takes in (ingestion), breaks up (digestion), absorbs (absorption), and eliminates wastes (egestion)

5. The GI Tract Essentially one long tube with two openings (mouth and anus) with accessory organs Gastrointestinal tract: Mouth  Esophagus  Stomach  Small Intestine  Large Intestine  Rectum  Anus Accessory organs: Salivary glands Liver gall bladder pancreas

6. Tissues of the Digestive System The entire digestive tract is lined with epithelial tissue Goblet cells secrete mucus Mucus protects the tract from digestive enzymes, and lubricates the passage for the food The tract also contains muscle which allows the food to be pushed along the tract (peristalsis) Warning... Gross video ahead

7. Mouth Starting point of digestion Mechanical digestion: Mouth and Tongue – break apart Food Chemical digestion: Saliva – Saliva contains enzymes that break down food. Saliva also lubricates the food. Once broken up, the food (now a bolus) is swallowed

9. Esophagus Long tube surrounded by muscle The muscle contracts and relaxes to push food along toward the stomach (peristalsis)

11. Stomach Muscular organ that holds and churns food to continue the process of digestion Strong acids (Hydrochloric acid HCl) and enzymes are secreted in the stomach to digest food Acid that splashes up into the esophagus is the cause of heartburn

12. Small Intestines Small intestine is actually quite long – approximately 6m Partially digested food that leaves the stomach is further digested Nutrients are absorbed

13. Large Intestines (Colon) Large intestine are about 1.5m in length, but larger in diameter than S. Intestine Water is reabsorbed Trillions of bacteria live in your colon They provide you with vitamins (K, and biotin)

15. Warning – Frog picture ahead