1. Human Digestive System

2. Two Main Types of Digestion Mechanical : Physically breaking apart food. This increases the surface area on which digestive enzymes can act!! Mechanical : Physically breaking apart food. This increases the surface area on which digestive enzymes can act!! Chemical : Uses enzymes to break down food. Enzymes increase rates of reaction of digestion so that they are fast enough that you can live. Enzymes are pH and temperature sensitive. Chemical : Uses enzymes to break down food. Enzymes increase rates of reaction of digestion so that they are fast enough that you can live. Enzymes are pH and temperature sensitive.

3. Digestive System video Digestive System video Also: TEDtalk1 TEDtalk1 TEDtalk1 TEDtalk2 TEDtalk2 TEDtalk2 DRAW:

4. MOUTH Mechanical: Your teeth grind and cut your food. Your tongue helps position food for grinding. Mechanical: Your teeth grind and cut your food. Your tongue helps position food for grinding. Chemical: Saliva is produced by the salivary glands. Saliva consists of water, mucus, and an enzyme called salivary amylase. Chemical: Saliva is produced by the salivary glands. Saliva consists of water, mucus, and an enzyme called salivary amylase. Salivary amylase starts to digest starch (polysaccharides) to maltose (disaccharide.) Salivary amylase starts to digest starch (polysaccharides) to maltose (disaccharide.)

5. ESOPHAGUS No digestion… No digestion… A bolus, a ball of food, is forced into the pharynx when you swallow. A bolus, a ball of food, is forced into the pharynx when you swallow. A protective flap, the epiglottis, prevents it from entering your trachea (your windpipe), and the bolus enters the esophagus. A protective flap, the epiglottis, prevents it from entering your trachea (your windpipe), and the bolus enters the esophagus. The esophagus is a muscular tube that connects the pharynx and stomach. The esophagus is a muscular tube that connects the pharynx and stomach. Muscular contractions force food through the esophagus to the stomach. Muscular contractions force food through the esophagus to the stomach. Clicker Question #1

7. Stomach: Mechanical Digestion J-shaped organ with three layers of muscle. J-shaped organ with three layers of muscle. Mechanical Digestion: Muscle twists and turns the stomach… churning the food contents inside. If you have eaten no food…. you hear it growl from contractions of the muscle. Mechanical Digestion: Muscle twists and turns the stomach… churning the food contents inside. If you have eaten no food…. you hear it growl from contractions of the muscle.

8. Stomach: Chemical Digestion Inner layer of stomach has small openings called gastric pits (open ends of glands) Inner layer of stomach has small openings called gastric pits (open ends of glands) Gastric glands secrete mucus, enzymes, and HCl…. acidic digestive juices! Gastric glands secrete mucus, enzymes, and HCl…. acidic digestive juices! Pepsin, an enzyme which functions only at a low pH, breaks down complex proteins into shorter chains of amino acids (catabolic reaction) Pepsin, an enzyme which functions only at a low pH, breaks down complex proteins into shorter chains of amino acids (catabolic reaction) HCl ensures a low pH and also kills bacteria that enter the stomach. HCl ensures a low pH and also kills bacteria that enter the stomach.

9. MUCUS is vital to stomach survival! WHY? MUCUS is vital to stomach survival! WHY? It forms a coating to protect the lining of the stomach from HCl and prevents pepsin from digesting proteins in stomach tissue. It forms a coating to protect the lining of the stomach from HCl and prevents pepsin from digesting proteins in stomach tissue. Food stays in stomach churning and mixing with gastric juices for 3-4 hours, then forms chyme, a creamy substance (ewwww….) Food stays in stomach churning and mixing with gastric juices for 3-4 hours, then forms chyme, a creamy substance (ewwww….) Chyme contains lipids, simple sugars, starches, vitamins, minerals, peptides, and large proteins that didn’t get broken down. Chyme contains lipids, simple sugars, starches, vitamins, minerals, peptides, and large proteins that didn’t get broken down. Chyme leaves stomach and enters the small intestine! Chyme leaves stomach and enters the small intestine!

10. Possible Pains Heartburn: Heartburn: When acidic juices from the stomach reflux back into the esophagus…you get a painful, burning sensation. This is mistaken for a heart attack sometimes! Ulcer: Ulcer: When pepsin starts eating away at proteins in the stomach lining…creates a lesion, called an ulcer… painful!

11. Clicker Questions #2&3

12. The Liver Multifunctional organ! Multifunctional organ! Stores glycogen, breaks down toxins, like H 2 O 2, ammonia, alcohol, etc. Stores glycogen, breaks down toxins, like H 2 O 2, ammonia, alcohol, etc. Also involved in mechanical digestion: Secretes Bile Also involved in mechanical digestion: Secretes Bile Bile assists in fat digestion, through “emulsification,” breaks large fat globules into smaller droplets = increases surface area Bile assists in fat digestion, through “emulsification,” breaks large fat globules into smaller droplets = increases surface area Bile goes to the gall bladder, where it is stored, until chyme is in the small intestine. Bile goes to the gall bladder, where it is stored, until chyme is in the small intestine. Once chyme moves into the small intestine, bile is released into the intestine to emulsify lipids. Once chyme moves into the small intestine, bile is released into the intestine to emulsify lipids.

13. Pancreas The pancreas is involved with chemical digestion in the small intestine. The pancreas is involved with chemical digestion in the small intestine. Secretes a fluid with a digestive enzyme called pancreatin. Secretes a fluid with a digestive enzyme called pancreatin. Pancreatin enters small intestine when chyme is present to be digested. Pancreatin enters small intestine when chyme is present to be digested. Pancreatin helps digest disaccharides into monosaccharides, fats into glycerol and fatty acids, and proteins (peptides) into single amino acids. Pancreatin helps digest disaccharides into monosaccharides, fats into glycerol and fatty acids, and proteins (peptides) into single amino acids. The pancreas also secretes two other very important enzymes: insulin and glucagon. The pancreas also secretes two other very important enzymes: insulin and glucagon. These enzymes regulate the amount of glucose that is in your blood. These enzymes regulate the amount of glucose that is in your blood.

15. Small Intestine (about 7 m long) Digestion Three parts: duodenum (small part), jejunum, ileum. Three parts: duodenum (small part), jejunum, ileum. First part: Duodenum Takes the secretions of substances (bile and pancreatin) to continue to breakdown food. Also, glands in the small intestine, secrete more enzymes to help break down food. First part: Duodenum Takes the secretions of substances (bile and pancreatin) to continue to breakdown food. Also, glands in the small intestine, secrete more enzymes to help break down food.

16. Small Intestine Absorption End products, amino acids, glycerol, fatty acid, monosaccharides, are absorbed into the circulatory system through blood vessels in the small intestine lining. End products, amino acids, glycerol, fatty acid, monosaccharides, are absorbed into the circulatory system through blood vessels in the small intestine lining. Small intestine is covered with millions of villi, which in turn have microvilli, which greatly increase the surface area of the intestine! Small intestine is covered with millions of villi, which in turn have microvilli, which greatly increase the surface area of the intestine! Why is this important? Why is this important? Entire surface area = 250 m 2 … the area of a tennis court! Entire surface area = 250 m 2 … the area of a tennis court! Nutrients are absorbed into blood and then go where they need to go. Nutrients are absorbed into blood and then go where they need to go.

18. Large Intestine Peristalsis (muscle contractions) moves remaining material to the large intestine. Peristalsis (muscle contractions) moves remaining material to the large intestine. Four parts: ascending colon, transverse colon, descending colon, sigmoid colon Four parts: ascending colon, transverse colon, descending colon, sigmoid colon Water is absorbed here… makes material solid = feces. Water is absorbed here… makes material solid = feces. Solid feces, with the help of mucus, move through intestine, through the rectum, then out through the anus. Solid feces, with the help of mucus, move through intestine, through the rectum, then out through the anus. Clicker Questions #4,5,6

19. Interesting Facts Many bacteria live in the large intestine, like E.coli Many bacteria live in the large intestine, like E.coli They live on digested material, and release gases such as methane and hydrogen sulfide due to their metabolism. They live on digested material, and release gases such as methane and hydrogen sulfide due to their metabolism. 40% of the mass of feces is intestinal bacteria! 40% of the mass of feces is intestinal bacteria! So, when lakes test positive for E.coli … raw sewage waste (untreated) has made it to the waters. So, when lakes test positive for E.coli … raw sewage waste (untreated) has made it to the waters. Diarrhea can result when you don’t absorb enough water in the large intestine and solid feces doesn’t form. Diarrhea can result when you don’t absorb enough water in the large intestine and solid feces doesn’t form. Constipation results when too much water is absorbed, and not enough moisture remains in feces. Constipation results when too much water is absorbed, and not enough moisture remains in feces.

25. Love your Intestines! LABELING YOUR DIGESTIVE SYSTEM COLORING SHEET: Top section: 1)Label the three salivary glands 2)Label where fat, carb and protein digestion STARTS 3)Label where you find amylase, pancreatin, bile, pepsin Bottom section: 1)Label enzymes involved in each section, carbs, proteins, fats Turn in! Thanks!

26. Summary of digestion See document on Anatomy calendar

27. Digestive Anatomy ws 1. Mesentery 2. Villi 3. Peyer’s patches 4. Plicae circulares 5. Oral cavity or stomach 6. Tongue 7. Pharynx 8. Greater omentum, lesser omentum, mesentery 9. Esophagus 10. Rugae 11. Haustra 12. Microvilli 13. Ileocecal valve 14. Small intestine 15. Colon 16. Vestibule 17. Appendix 18. Stomach 19. Lesser omentum 20. Small intestine 21. Pyloric sphincter 22. Soft palate 23. Small intestine 24. Parietal peritoneum 25. Anal canal 26. Hard palate

28. Incredible Journey! 1. Oral cavity16. villi 2. Vestibule17. ileocecal valve 3. Tongue 4. Salivary amylase 5. Peristalsis 6. Esophagus 7. Trachea 8. Epiglottis 9. Stomach 10. Mucus 11. HCl 12. Pepsin 13. Pyloric sphincter 14. Bile 15. Gall bladder