Metabolism

1. FOOD sugars fats proteins simple sugars (glucose) fatty acids amino acids lipids glycogen proteins glucose glucose muscle liver fat glucose glucose glucose Metabolism

2. Gall bladder liver Bile Duct Pancreas Pancreatic duct duodenum Mammalian Pancreas -Exocrine Pancreas: secretes digestive enzymes, alkaline pancreatic fluid -Endocrine Pancreas: secretes hormones that regulate carbohydrate, lipid, and protein metabolism

3. Islets of Langerhans Exocrine cells    capillaries Endocrine Pancreas • Islets of Langerhans: 4 cell types •  cells: secrete glucagon •  cells: secrete insulin •  cells: secrete somatostatin • F cells: secrete pancreatic polypeptide

4. Pancreatic Hormones • Insulin • Glucagon • Somatostatin

5. INSULIN • Regulation of Secretion • Hyperglycemia stimulates release • Glucose sensors in  cells • Gastric Inhibitory Peptide • Released from cells of the small intestine • Potent stimulator of insulin secretion • Somatostatin: inhibits insulin release (paracrine) • Autonomic nervous system • Parasympathetic activation increases insulin release • Sympathetic activation blocks insulin release • Epinephrine (from adrenal) blocks insulin release

6. INSULIN • Action at Target Tissues • Activation of insulin receptor: • Increases transport of glucose, amino acids, and fatty acids into cells Glucose transporter:

7. INSULIN • Action at Target Tissues • Activation of insulin receptor: • Increases transport of glucose (glucose transporter), amino acids, and fatty acids into cells • Enhancement of anabolic pathways, decrease in catabolic pathways • Increases enzymes that activate: • Glycogen formation (liver) • Lipogenesis (fat) • Protein Synthesis (muscle)

8. Pancreatic Hormones • Insulin • Hypoglycemic, glycogenic, lipogenic, anabolic • Glucagon • Somatostatin

9. Glucagon • Hyperglycemic (increases plasma glucose) • (one of many in the body) • Actions at target cells • Liver • Promotes glycogenolysis • Promotes gluconeogenesis • Fat Tissue • Promotes lipolysis

10. Pancreatic Hormones • Insulin • Hypoglycemic, glycogenic, lipogenic, anabolic • Glucagon • Hyperglycemic, lipolytic • Somatostatin • Paracrine agent • Believed to inhibit insulin and glucagon release • May regulate uptake of nutrients from the gut

11.  Insulin: decreases blood glucose levels  Glucagon: increases blood glucose levels  Somatostatin: regulates insulin and glucagon levels (paracrine) and nutrient uptake at the gut Glucose Regulation

12. DIABETES MELLITUS • Type I—juvenile onset—insulin dependent • IDDM • Underproduction of insulin • Type II—adult onset—non-insulin dependent • NIDDM • Insulin receptor resistance • Post-receptor mechanism problem

13. Insulin Dependent: IDDM • Possibly results from autoimmune reaction • The body’s immune system attacks the  cells • Pancreatic  markedly reduced • Symptoms only appear after ~80% loss of cells • No insulin……physiological repercussions? • Treatment • Insulin injections • Recent methods

14. Separate islets from exocrine pancreas Encapsulate islets (immune protection) Inside the patient Inject into abdomen Islet Transplantation

15. Non-Insulin Dependent: NIDDM • Usually occurs in overweight individuals over 40 years of age • Associated with abdominal fat in women • Target cells become resistant to insulin • insulin receptor • Fewer receptors • Receptors have lower affinity • Receptor blocked (possibly by antibody) • Post-receptor mechanisms

16. Diabetes Prevelence in US %