1. H. Tanner, Late 1800’s: “Shepherds and Angels”

2. The Digestive System Chapter 16: 446-455

3. “The importance of daily defecation has been greatly overestimated.” Seeley, Stephens And Tate, 1999

4. Digestion, Absorption and Transport of Macronutrients Macronutrients: Carbohydrates, Lipids and Proteins Digestion: Mechanical and chemical breakdown of food Absorption: Diffusion of nutrients into blood from intestine Transport: “Escort” of nutrients into the blood

5. Anatomy Oral cavity Pharynx Esophagus Stomach Small Intestine Liver Pancreas Large Intestine

6. Did You Know? In Diabetes Mellitus, the cells of the body are starving even though blood glucose levels may be 400% normal values or more???

7. Normal Carbohydrate Metabolism Carbohydrate Foods: Starches: Chains of sugars Sugars: Glucose, Fructose, Lactose etc. Cellulose: Indigestable (“roughage”) Useable Form: GLUCOSE

8. Converting Carbohydrate Food to GLUCOSE: Digestion: Chewing: Mechanical disruption SalivaryEnzymes: Amylase: POLYSACCHARIDES Pancreatic Enzymes: Amylase: DISACCHARIDES SI Disaccharidases MONOSACCHARIDES

9. The Final Step to Glucose: Monosaccharides: Absorbed into Hepatic Portal System Liver Delivery LIVER: Conversion to Glucose or Glycogen Glucose: Transported in blood to body cells/brain

10. Why are Cells Starving in a Person with Diabetes? What hormone is associated with Diabetes? Why is that hormone necessary? Why do some people have to inject Insulin, and others don’t?

11. What Hormone and Why? Insulin: Targets muscle and adipose cells Action: Stimulate recruitment of new Glucose Transporters to cell membranes Result: Increase Glucose uptake of those cells/ reducing blood glucose levels

12. IDDM vs. NIDDM Insulin Dependent Pancreatic  - Cell Failure Generally develops during childhood Non-Insulin Dependent Target Cell Receptor Fails Generally develops during adulthood

13. 1. Insulin 3. Glucose Glucose 2. Glucose Transporters Insulin Action: Muscle and Adipose Cells

14. Without Insulin Activity The Brain Still uses Glucose Muscle/Adipose Cannot Use Glucose They Starve! Fat utilization increases tremendously! Metabolic Acidosis Results

15. Did You Know? Alcohol has almost as many calories as fat, and excess amounts are converted into excess acetlyaldehyde (sounds like “formaldehyde”) which is toxic to the liver

16. Normal Lipid Digestion Lipids: Insoluble in H 2 O Types of Lipids: Phospholipids Steroids Triglycerides: Saturated and Unsaturated

17. Step One: Emulsification: Transforming large lipid droplets into smaller ones Liver Bile Salts: Secreted into the Duodenum Why? So H 2 O soluble enzymes can act on surface of very small lipid droplets

18. Step Two: Lipases: (Pancreas and Intestinal cells) Digest Lipids into Fatty Acids Glycerol Intestinal Bile Salts: Package into “Micelles” Now H 2 O Soluble

19. Step Three: Transported in Intestines as Micelles Absorption: Micelles fuse to intestinal epithelium – Triglycerides diffuse into cell Protein Coat Added H 2 O Soluble complex diffuses into lymph circulation

20. Step Four: Once in the general Circulation the “Fate of Fats”: Transported to the Liver: 1. Stored 2. Converted to other molecules 3. Used for Energy 4. Transported to Adipocytes for Storage

21. What Do You Know About Cholesterol?

22. Cholesterol: Stabilizes Cell Membranes Used to Make Bile Salts Used to make Steroid Hormones Obtained in food and Made “Runs with Proteins” (LDL/HDL) Is Associated with Heart Disease

23. Dietary Cholesterol Not the Big Problem Saturated Fats High Insulin Levels (Caused by eating diets high in Twinkies etc. and by inactivity/obesity) Familial Hypercholesterolemia: An LDL receptor defect

24. LDL vs. HDL Low Density Lipoprotein Protein “escort” is only 25% protein Excess LDL deposit on arterial walls High Density Lipoprotein Protein “escort” is 45% protein Excess HDL is transported to liver for excretion

25. Did You Know? The Body cannot store Excess Amino Acids from High Protein Diets! (But don’t think those calories are lost…)

26. Protein Digestion and Absorption: Pepsin: Breaks ~ 20% of the peptide bonds in the stomach Trypsin: Further shortens polypeptides to very short Peptide Chains Peptidase: Completes the digestion to amino acids in the small intestine

27. Amino Acid Absorption: Active Transport: Into Intestinal Cells Active Transport: Into Hepatic Portal System: Liver: Distribution Protein Synthesis Energy: Converted to Glucose Excess stored as fat / glycogen

28. Assignment: Answer Questions: 456:27-29 Write a Paragraph: Cystic Fibrosis affects the Digestive System as well as the Respiratory System: How is digestion affected? (see page 447)