1. Islets of Langerhan. Prof. K. Sivapalan

2. 08-01-14Islets of Langerhan2 Histology. A cells 20 % [glucogon] B cells 50% [Insulin] D cells 8% [somatostatin] F cells [pancreatic polypeptide]

3. 08-01-14Islets of Langerhan3 Insulin secretion. Amolecule with A and B peptide chains. Half life- 5 minutes.

4. 08-01-14Islets of Langerhan4 Mechanism of Actions of Insulin Insulin receptors are found in almost all cells. Insulin binds to the receptor. The receptor activates several different actions depending on the nature of the cell.

5. 08-01-14Islets of Langerhan5 Actions of Insulin on Carbohydrate Metabolism.. Glucose transporters are increased by increased levels of insulin. Glucose enters cells by facilitated diffusion- exceptions are, brain, Small intestinal epithelium, PCT in kidney. Glycogen storage increased in Liver and Muscle. Increases glycogen synthesis and reduces glycolytic enzymes.

6. 08-01-14Islets of Langerhan6 Actions of Insulin on Fat and Protein Metabolism Increases lipogenesis in liver and adipose tissue. Reduces lypolysis. Activates transport of Amino Acids into cells. Increases protein synthesis. * increases intracellular potassium.

7. 08-01-14Islets of Langerhan7 Insulin Action [Timed]: Rapid- [Seconds] –Increased transport of glucose, amino acids, and K + into insulin sensitive cells. Intermediate- [minutes] –Stimulation of protein synthesis. –Inhibition of protein degradation. –Activation of glycogen synthetase. –Inhibition of Phosphorylase and gluconeogenic enzymes. Delayed [hours] –Increase in mRNA for lipogenic and other enzymes.

8. 08-01-14Islets of Langerhan8 Regulation of insulin secretion. Feed back by glucose.

9. 08-01-14Islets of Langerhan9 Sudden increase of glucose. Sudden increase of blood glucose results in immediate rise in blood insulin and a second slow increase. ? Risk of fast food and benefit of natural food by slow digestion and steady absorption.

10. Causes of Diabetes Primary- primarily pancreatic problem Secondary- other diseases resulting in DM Type I- autoimmune, young age (insulin deficiency) Type II- main determinants- age, obesity, ethnicity and family history. (insulin resistance) –Metabolic syndrome- hypertension, obesity, hypertriglyceridaemia, decreased HDL, acanthosis nigricans. 08-01-14Islets of Langerhan10

11. 08-01-14Islets of Langerhan11 Diabetes Mellitus. Hyperglycemia, intracellular glucose deficiency Polyurea, (glycoseurea), Polydipsia. Weight loss, Polyphagia Retinopathy, neuropathy, erectile dysfunction Arterial disease- MI, Gangrene Poor resistance to infection- Skin infections Ketosis, acidosis, coma. Impaired glucose tolerance.

12. Principle of Management Diet Exercise Drugs –Stimulants –Utilization of glucose –insulin 08-01-14Islets of Langerhan12

13. 08-01-14Islets of Langerhan13 Hyperinsulinism. Cause- insulinoma or injection (accidental overdose or under eating). Early indications- tremor, palpitation, anxiety. Confusion, weakness, dizziness, hunger, convulsions, coma, death within a few minutes. –Glucose need for brain- 1 mg/min/kg body weight (100g/day for 70 kg man) It is a Medical emergency. * Importance of carrying glucose and diagnosis card if on insulin injection.

14. 08-01-14Islets of Langerhan14

15. 08-01-14Islets of Langerhan15 Glucagone. Peptide with 29 aminoacids, half life- 5-10 minutes. From A cells of pancreas and gastric and duodenal mucosa. Actions- just opposite of insulin.

16. 08-01-14Islets of Langerhan16 Regulation of Glucagon Secretion