1. Digestion and Nutrition - 2013 Overall Goal of Digestive Systems A. Obtain organic molecules from environment B. Reduce complex molecules such as proteins, polysaccharides, nucleic acids and lipids to absorbable sizes and C. Transport the molecules into the blood stream so that they may be assimilated into cells. General Strategies for obtaining nutrients A. Filter feeders - microorganisms, marine and freshwater crustaceans, baleen whales. (show whale video) http://videos.howstuffworks.com/discovery/428-corwins-quest-whales-video.htm http://videos.howstuffworks.com/discovery/28113-assignment-discovery-baleen-whales- plates-video.htm

2. B. Carnivores C. Herbivores 1. the problem with cellulose - requires bacteria or protozoa that produce cellulase 2. pregastric fermentation 3. postgastric fermentation D. Omnivores E. Symbiotic nutrition chloroplasts from algae in the bodies of sea slugs - photo synthetic products feed slugs http://www.newscientist.com/article/dn16124-solarpowered-sea-slug- harnesses-stolen-plant-genes-.html bacteria in digestive tracks of ruminants (cows) http://www.teachersdomain.org/resource/nat08.living.str.living.digest

3. Perspectives on Digestion Overview Mechanical - mastication, stomach, crop, and intestinal motility Chemical (secretions) - enzymes from saliva, pancreas and intestines Absorption - intestinal lumen o blood Assimilation - blood into cells throughout the body. Motility Smooth muscle Pace setter potential - specialized cells in digestive tract produce electric impulses(potentials) that stimulate the gut to contract Enteric (intrinsic) nervous control (responds to stretch, pH, hormones) Extrinsic = controlled by central nervous system (brain & spinal cord)

4. Fig. 14-5, p.619 Intrinsic Nerves of the Rat’s Stomach

5. Motility Storage of waste Defecation Secretions Ingestion Mouth Pharynx Receiving Foregut Crop Conducting Storage Digestion Midgut (stomach) Digestion (acidic) Hindgut Digestion (basic) Absorption Assimilation Fig. 14-1, p.613

6. The enzyme “cellulase” is required to hydrolyze cellulose. This enzyme is only produced by microorganisms. Animals must provide organs that support the growth of these symbionts. Starch is hydrolyzed to maltose by the enzyme “amylase” which is produced by the salivary glands and the pancreas.

7. Hydrolysis of a disaccharide (maltose) to two monosaccharides (glucose) Maltase is the enzyme that performs this action. It is produced primarily by the cells that line the intestinal lumen.

8. Categories of Digestive Enzymes Amylase: starch hydrolysis to maltose Protease: proteins hydrolyzed to peptides Lipase:triglycerides hydrolyzed to fatty acids and glycerol Nucleotidasesnucleic acids hydrolyzed to nucleotides

9. Gastrointestinal Tract (alimentary canal) mouth-anus Accessory Organs Liver Gall Bladder Pancreas

10. Fig. 14-7a, p.624 Tongue (a) Trachea Esophagus Epiglottis Pharynx Uvula Soft palate Hard palate Nasal passages Glottis at entrance of larynx Bolus

11. Peristalsis - a local reflex

12. Fig. 14-8, p.627 Duodenum Smooth muscle Fundus Esophagus Gastroesophageal sphincter Body Stomach folds Oxyntic mucosa Antrum Pyloric gland area Pyloric sphincter

13. Table 14-3b, p.632 Gastric pit Mucosa Submucosa

14. Table 14-3c, p.632 Gastric gland Surface epithelial cells Gastric pit Chief cells Mucous cells Enterochromaffin- Like (ECL) cells In oxyntic mucosa Parietal cells Produce pepsinogen Produce HCl and Intrinsic Factor

15. Peptic Ulcers Heliobacter pylori - bacterial infection responsible for 90% of all peptic ulcers Treatment with antibiotics

16. Fig. 14-11, p.634

18. HCl, fats, osmo CCK Secretin

19. Intestinal Cross Section Layers of the alimentary canal Serosa Muscularis Submucosa Mucosa Smooth muscle cells Villus (Villi) Microvilli Mucosal cells

20. Fig. 14-20, p.647

21. Large fat droplet Lipid emulsion Small lipid (fat) droplet with bile salt molecules adsorbed on its surface Lipid-soluble portion (derived from cholesterol) Negatively charged H2O- soluble portion (a carboxyl group at the end of a glycine or taurine chain) Through action of bile salts Fig. 14-17, p.644

22. Fig. 14-24a, p.654 Lipid Absorption

23. Fig. 14-14, p.641

24. Fig. 14-16, p.642

25. Block Diagram of Lipid Absorption Lipids in Duodenum Lipids combine with Bile and form Micelles Micelles taken up by mucosal cells Mucosal cells add proteins and extract fatty acids Lipase begins to convert triglycerides to fatty acids Lipids enter lymph capillaries as Chylomi ra Chylomicra move through lymphatic system and enter the blood at subclavian veins. Liver takes up Chylomicra and converts them to HDL’s and LDL’s HDL’s and LDL’s re- enter blood and are distributed to other cells throughout the body.

27. Fig. 14-26, p.657 Transverse colon Internal anal sphincter (smooth muscle) Taeniae coli Ileocecal valve Ascending colon Rectum Cecum Appendix Anal canal External anal sphincter (skeletal muscle) Sigmoid colon Descending colon Haustra

28. Fig. 14-27b, p.661 Reticulum (b) To small intestine Rumen Abomasum Omasum