1. Animal Nutrition With a side bar on the animal kingdom!

2. Animal Phylogeny P.640 32.8 P.640 32.8

3. Why Digest? Makes food available to cells Makes food available to cells May be intracellular-within each individual cell May be intracellular-within each individual cell May be extracellular- enzymes are released and food is prepared for all cells. May be extracellular- enzymes are released and food is prepared for all cells.

4. Intracellular is primitive Phylum Porifera Porifera Picture Porifera Picture

5. Extracellular with one body opening and gastrovascular cavity Phylum Cnidaria Phylum Platyhelminthes Cnidaria cross section Cnidaria cross section Planaria cross section Planaria cross section

6. Extracellular with one way digestive tract (have mouth and anus) Phylum Nematoda Phylum Annelida Nematode Pix Nematode Pix Annelids Annelids Annelid cross section Annelid cross section

7. Animals are group based on food source Carnivores- eat meat- shorter intestine, pointed teeth. Omnivores- eat meat and plants, teeth like carnivore in front and herbivore in back. Herbivores- eat plants, longer intestine, large flat teeth to break up plant tissue. Long very specialized digestive tract. Bear Pix Bear Pix

8. Herbivore modifications 41.22 41.22

9. Specialized Actions Mechanical-teeth, grinding(pebbles in bird and earthworm gizzards), churning. Mechanical-teeth, grinding(pebbles in bird and earthworm gizzards), churning. Chemical-hydrolysis by enzymes Chemical-hydrolysis by enzymes Ex:Salivary amylaseEx:Salivary amylase Source-salivary glandSource-salivary gland Substrate-starch-a polysaccarideSubstrate-starch-a polysaccaride Product-maltose- a disaccarideProduct-maltose- a disaccaride

10. Human Digestive System Food moves by peristalsis Digestive System Pix Digestive System Pix

11. Accessory Organs Liver-produces bile Gallbladder-stores and concentrates bile Pancreas-produces pancreatic juice (both enzymes and bicarbonate) 41.16 41.16

12. Stomach-Site of Protein Digestion Convoluted Secretes Gastric Juice-acidic secretions of gastric glands of mucosa Two cell types- Parietal-HCl Chief-pepsinogen- activated in low pH-to form pepsin Low pH denatures proteins Protein digestion finished in small intestine Output from stomach-chyme 41.15 41.15

13. Protein Digestion Pepsin Source-chief cells as pepsinogen Substrate-protein Product-polypeptides Optimum pH-2 Trypsin Source-pancreas as trypsinogen Substrate- polypeptide Product-amino acids Optimum pH-neutral 41.18 41.18

14. Small Intestine- Carbohydrate, lipid, protein digestion finished. Carbohydrate, lipid, protein digestion finished. Everything absorbed (exceptions-aspirin, alcohol, water - absorbed in stomach) Everything absorbed (exceptions-aspirin, alcohol, water - absorbed in stomach) First 25 cm-duodenum- receives secretions from pancreas, gall bladder. First 25 cm-duodenum- receives secretions from pancreas, gall bladder. Then jejunum Then jejunum Then ileum Then ileum 41.21 41.21

15. Structure of the GI Tract Inner mucosa- epithelium Submucosa- connective Muscularis-double layer of smooth muscle Serosa-more connective tissue 41.19 41.19

16. SI Absorption Brush Border-where a.a’s and monosac’s are transported into the epithelial cells, across membranes and into blood capillaries within the villi. From here carried to the liver Fat-hydrolyzed, absorbed, reassembled into triglycerides. Triglycerides combine with protein to form chylomicrons- absorbed into lymphatic system-empties into veins near the neck. 41.19 41.19

17. Large Intestine Large in diameter Large in diameter Joins SI near two vestigial organs Joins SI near two vestigial organs Appendix and cecumAppendix and cecum Vitamin K made by microorganism here and absorbed. Vitamin K made by microorganism here and absorbed. Bacteria ferment here- produce gas Bacteria ferment here- produce gas Low fiber diets-food moves slowly- associated with high colon cancer rates Low fiber diets-food moves slowly- associated with high colon cancer rates

18. Pancreas Secretes Pancreatic juice-enters duodenum through the pancreatic duct. Contains Secretes Pancreatic juice-enters duodenum through the pancreatic duct. Contains Trypsin-proteinTrypsin-protein Chymotrypsin-proteinChymotrypsin-protein Pancreatic amylase-starchPancreatic amylase-starch Lipase-fatLipase-fat Bicarbonate-neutralizes HCl makes alkalineBicarbonate-neutralizes HCl makes alkaline Secreted as zymogens-inactive enzymes Secreted as zymogens-inactive enzymes Activated by brush border enzymes Activated by brush border enzymes Digestion is completed by brush border enzymes Digestion is completed by brush border enzymes

19. Liver Largest internal organ Secretes bile Bile pigment-from RBC’s-no digestive role-too much jaundice Bile salts-work like detergent to emulsify Stored in gall bladder-fatty food triggers release Regulatory Metabolizes drugs, alcohol Removes steroid hormones Produces most blood proteins Regulates blood glucose-stored in liver as glycogen, used up-does gluconeogenesis

20. Regulation of digestion Coordinated by nervous/endocrine Coordinated by nervous/endocrine Sight/smell-nervous Sight/smell-nervous Food in stomach-release of gastrin-causes release of gastric juices Food in stomach-release of gastrin-causes release of gastric juices Hormones control passage of food into duodenum-high fat slows passage Hormones control passage of food into duodenum-high fat slows passage Duodenum secretes CCK in response to fat-causes bile release Duodenum secretes CCK in response to fat-causes bile release Secretin-causes pancreas to release bicarbonate Secretin-causes pancreas to release bicarbonate