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Fuel Homeostasis 2
Duke PA physiology
| Question | Answer |
|---|---|
| What are the insulin target cells? | muscle, liver, fat |
| What does insulin do to its target cells? | stimulates uptake of glucose into the cells |
| What do the islet alpha cells of the pancreas secrete? | glucagon |
| What effect does a rise in glucagon have on insulin? | glucagon turns on insulin |
| Does insulin stimulate or inhibit glucagon? | inhibit |
| What level does plasma glucose need to be maintained at? | 80-100 mg/dL |
| How does glucose enter the cell? | through the GLUT2 transporter |
| what is Glc converted to? | Glc6P |
| What is GLlc6P converted to? | ATP |
| Is the GLUT2 transporter regulated by insulin? | NO - these transporters are present on all cells |
| Why is glucose phosphorylated? | traps it in the cell - keeps it from going out |
| What phosphorylates glucose? | a kinase |
| What effect does rise in ATP have on the cell? | closes ATP sensitive K+ channel |
| What does the closing of the K+ channel have on the cell? | depolarizes the beta cell |
| What does depolarization of the cell cause? | opening of Ca voltage channel |
| What does Ca entry increase? | DAG + IP3 |
| What does increase in DAG + IP3 lead to? | release of Ca++ from the ER |
| What does rise in Ca++ lead to? | exocytosis of insulin |
| What does opening of voltage gated K+ channel cause? | repolarization of the cell |
| What is MODY? | mature onset diabetes of the young (type 2) |
| What step doesn't occur correctly in MODY? | phosphorylation of glucose in the cell |
| What does lack of phosphorylation cause in MODY? | high circulating levels of glucose in the blood |
| What do sulphonylnurea drugs do? | close potassium channel - resulting in depolarization of the cell |
| How long do normal individuals take to remove glucose? | 2 hours |
| What does a glucose tolerance test check? | see if it takes longer than normal to clear glucose |
| What does GLP-1 signal? | pancreatic islet beta cell to secrete insulin |
| What does plasma aa signal to the pancreas? | turns on the pancreatic islet beta cell |
| What effect on insulin secretion does the parasympathetic NS activity have? | turns it on |
| What effect does sympathetic NS activity & plasma epi have on insulin? | inhibit pancreate islet beta cell |
| What transporters on the cell surface of muscle, liver and fat are turned on by insulin? | GLUT4 - recruited to the cell surface |
| What is one of the first sign of diabetes type II? | In muscle, do not recruit GLUT4 transporters to cell surface in presence of insulin |
| What is pathology associated with glucose? | too little glucose inside cells, too much glucose outside cells |
| What does glucose outside of the cells cause? | problem - bind to proteins. Also, exceed renal threshhold for glucose, and urine will not be as concentrated - causes increases thirst. Starved for fuel, lose weight. |
| What causes insulin insuffiency in type 1 diabetes (IDDM)? | destruction of the pancreatic islets |
| What is the treatment for type 1 diabetes mellitus? | insulin replacement therapy |
| What causes insulin insuffiency in type 2 diabetes (NIDDM)? | altered response of the beta cell to a rise in plasma glucose |
| Are target cells sensitive to insulin in type 2 diabetes? | no - they are less sensitive to insulin - "insulin resistant" |
| What metabolism prevails in type 1 diabetes? | catabolic metabolism |
| Which type of diabetes does metabolic ketoacidosis occur in? | type 1 |
| What can weight loss cause in type 2 diabetes? | decrease free fatty acids, make target cells more sensitive to insulin |
| What test would you do to check for diabetes? | fasting overnight glucose tolerance test |
| What is the difference in the plasma glucose in a diabetic human (type 1)? | plasma glucose rises to higher level (>200mg/dL at 2 hr) and remains elevated longer |
| What type of insulin response is present in type 1 diabetes? | no insulin response - no beta cells, so no insulin at all |
| What is fasting glucose level in type 1 diabetic individual? | elevated >126 mg/dL |
| What happens to receptors in type 2 diabetes? | down regulation |
| What insulin levels occur in anabolic metabolism? | high |
| What senses a decrease in plasma glucose? | pancreatic islet alpha cells |
| What do pancreatic islet alpha cells cause? | increase in glucagon secretion |
| What does glucagon cause? | increase in plasma glucagon |
| What does plasma glucagon cause in the liver? | increased glycogenolysis, increase gluconeogensis, increased ketone synthesis |
Created by:
ges13
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