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The Digestive System Period 3, Haas (Q2 2011) Bo Dunham, Kelsey Williams, Hanna Shokouhi, Kyle Love Digestive System • • • • • • • • • • • Mouth Esophagus Stomach Small Intestine Liver Gallbladder Pancreas Large Intestine Colon Rectum Anus Mouth • Mechanical Digestion: Chewing food and breaking it into smaller pieces • Chemical Digestion: Begins with amylase in saliva released by salivary glands • Amylase: begins to break down starches (polysaccharides to monosaccharides) Esophagus • After swallowing, moves food from the mouth to the stomach • Rhythmic contractions of muscles along sides to push food to stomach (peristalsis) Stomach • Food mixes to make chyme • Chyme is a mixture of the partially broken down food and chemicals • Chemical digestion begins in the stomach with the HCl (hydrochloric acid) and other chemicals • Another chemical that breaks down proteins is pepsin which is the active form of pepsinogen. It becomes active in the presence of HCl • The stomach is protected from the HCl by the mucous membrane. When that fails to be made properly, such as during chemotherapy, the HCl begins to break down the stomach lining and causes ulcers Small Intestine • • • • • Chyme enters the small intestine (beginning is the duodenum) from the stomach through the pyloric valve Where the most nutrient absorbtion occurs Enzymes help with absorbtion that come from the parcreas (sodium bicarbonate) and liver (bile) When chyme enters the small intestine the carbs and proteins are only partially digested, digestion finishes here Villi (singular- villus) are small folds in the lining of the small intestine that increase the surface area to absorb more nutrients Liver • Secreates bile (not an enzyme) • Bile is stored in the gallbladder until it is inserted into the small intestine to help with digestion. Helps break down fat by emulsifying it and not letting it congeal • Emulsify: to break into smaller pieces • Molecules of bile are amphipathic so they stick to the fat on one side and repel from each other, breaking the fat apart Emulsification Web Resources • http://www.5min.com/Video/Learn-howthe-Digestive-System-Works-117554716 • http://www.5min.com/Video/Ways-to-HelpYour-Digestive-System-93890102 • http://www.5min.com/Video/Learn-aboutthe-Digestive-System-117551302 • http://vimeo.com/15992520 Pancreas • Located behind the stomach • Secreates sodium bicarbonate (not an enzyme) which it releases into the small intestine to help digestion • Sodium bicarbonate: liquid chalk • Very basic solution (as compared to acidic chyme) so helps to neutralize the environment in the small intestine Large Intestine • After the small intestine the indigestible material enters here • The main function of the large intestine is to reabsorb the water from the indigestible material • Amount of water left in indigestible material determines consistency of excretion • Some bacteria also located here that helps break down indigestible carbohydrates (lactase) and synthesize vitamin B and K complexes Colon, Rectum, Anus • Colon: The last few inches of the large intestine • Rectum: Where the indigestible material is collected before it is released. • Anus: Last opening through which indigestible material is expelled Practice Questions 1. What type of break down occurs in the mouth? A. Mechanical B. chemical C. Both 2. What enzyme is released by your salivary glands? A. Bile B. HCl C. Amylase 3. What connects the mouth to the stomach? A. The large intestine B. the liver C. The esophagus 4. What is the contraction of the smooth muscles in the esophagus? A. Hector B. peligalus C. peristalsis D. Bo 5. What is the large muscle sack that the esophagus connects to? A. Liver B. Gallbladder C. Stomach Practice Questions 6. What makes the stomach acidic? A. H2O B. Cl C. HCl 7. What is released into the stomach that speeds up digestion? A. Pepsinagen B. Pepsi C. Pepsin 8. Pepsin breaks ______ into small peptide fragments. A. Fats B. Carbs C. Protein 9. What type of digestion takes place in the stomach? A. Chemical B. Mechanical C. Both 10. Chyme is _______? A. Secreted by the pancreas B. produced by the liver C. made in the stomach Practice Questions 11. From the stomach, your food goes to the ____? A. Liver B. large intestine C. small intestine 12. Most of the digestions occurs in the _____? A. Stomach B. large intestine C. small intestine 13. Where is the pancreas located? A. The brain B. left pinky toe C. behind the stomach 14. What does that pancreas make that neutralizes stomach acid? A. HCl B. bile C. Sodium Bicarbonate 15. The small intestine has circular folds that contain _____. A. Sodium B. HCl C. villi Practice Questions 16. The _____ is after the small intestine. A. Rectum B. stomach C. large intestine 17. The large intestine does ____. A. Absorb bile B. take HCl from waste C. removes the water 18. The large intestine produces ______. A. HCl B. bile C. Vitamin B and K 19. Stuff exits the body through the ____. A. Mouth B. stomach C. anus 20. The coolest student in Mr. Haas’s class is? A. Kelsey B. Bo C. Alana and Bridget D. Love Key C