1. A and P II Glucose Metabolism

2. 120 grams of glucose / day = 480 calories

4. Saccharides Glucose is the primary monsaccaride in the body (one sugar) There are dissaccarides like fructose, sucrose, galactose Starches and glycogen are polysaccarides

5. How is sugar made/absorbed? Amylase-(pancreatic and salivary)breaks starches into dia+trisaccharides Lactase,maltase,sucrase-enzymes in small intestine that break up dissaccharides into small glucose Then absorbed and transported in blood

6. Where does it go after it is absorbed?

7. The Pancreas Organ (5 inches) consists of head, body & tail Has both an exocrine & an endocrine function –acinar cells produce digestive enzymes –endocrine cells (Islets of Langerhans) produce hormones

8. Cell Organization in Pancreas Exocrine acinar cells surround a small duct Endocrine cells secrete near a capillary

9. Histology of the Pancreas 1 to 2 million pancreatic islets Contains 4 types of endocrine cells

10. Cell Types in the Pancreatic Islets Alpha cells (20%) produce glucagon Beta cells (70%) produce insulin Delta cells (5%) produce somatostatin

11. Regulation of Glucagon & Insulin Secretion Low blood glucose stimulates release of glucagon High blood glucose stimulates secretion of insulin

12. Insulin Released in response to rising blood glucose levels Decreases glucose levels by promoting: –The rapid up-take of glucose by cells –Storage of glucose (stored as glycogen in the liver) –Promotes the use of glucose by most body tissues –Promotes the conversion of excess glucose to fat –Inhibits gluconeogenesis from protein = “hypoglycemic effect”

13. Insulin Cell Use of Glucose for ATP production

14. Glucagon Released from alpha cells in pancreas in response to decreasing blood glucose levels Increases blood glucose levels by promoting : –Glycogenolysis of liver glycogen –Gluconeogenesis in liver cells –Mobilizes fatty acids for energy = “hyperglycemic effect”

15. It is important to maintain blood glucose levels within a narrow range Glucose is the only nutrient that the brain, retina & germinal epithelia of the gonads can use The liver acts as an important “buffering mechanism” Insulin & glucagon function in opposite directions Insulin is more important day-to-day Glucagon is usually only present in times of stress

16. Pathologies of Blood Glucose Regulation 1.Diabetes mellitus –Decreased insulin secretion from the beta cells –2 types:Type I (juvenile) Type II (adult onset) 2.Hyperinsulinism- too much insulin e.g tumour

17. Diabetes Mellitus Type I –Hereditary predisposition to autoimmune disease of beta cells –Or destruction of beta cells (ie: viral infection) Type II –Degeneration or suppression of the beta cells –Precipitated by factors such as obesity, stress, pregnancy, menopause Pathogenesis –Altered glucose, fat & protein metabolism

18. Signs –Glucose in urine –Dehydration –Acidosis Symptoms –Polyuria, Polydipsia & Polyphagia –Loss of weight –Lack of energy –Acetone breath –Rapid deep breathing Diabetic coma can be fatal & results from severe dehydration & acidosis Treatable…..Yes

19. Regulation of Glucose Metabolism During Exercise Glucagon secretion increases during exercise to promote liver glycogen breakdown (glycogenolysis) Epinephrine and Norepinephrine further increase glycogenolysis Cortisol levels also increase during exercise for protein catabolism for later gluconeogenesis. Growth Hormone mobilizes free fatty acids Thyroxine promotes glucose catabolism

20. Regulation of Glucose Metabolism During Exercise Glucose must not only be delivered to the cells, it must also be taken up by them. That job relies on insulin. Exercise may enhance insulin’s binding to receptors on the muscle fiber. Up-regulation (receptors) occurs with insulin after 4 weeks of exercise to increase its sensitivity (diabetic importance).

21. If glucose is Not available First use exogenous blood sugar (in blood) Then break up glycogen in liver etc Then break up fatty acids from triglycerides (fat stores) etc which produce ketones as a by produce Also work on proteins then to try to convert to energy the body can use

23. Stage 1 – postparandial –All tissues utilize glucose Stage 2 – postabsorptive KEY – Maintain blood glucose –Glycogenolysis –Glucogneogenesis –Lactate –Pyruvate –Glycerol –Spare glucose by metabolizing fat Stage 3- Early starvation –Gluconeogenesis Stave 4 – Intermediate starvation –gluconeogenesis –Ketone bodies Stage 5 – Starvation

24. Reading sugar metabolism of Endocrine section Saladin Look in your Caroline book as well on endocrine disorders Note: Normal blood sugar is 4.0-6.0 mmol/L