Regulation of insulin levels
- Created by: Steff06
- Created on: 22-03-16 16:54
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- Insulin regulation
- Control of insulin secretion:
- 1. The cell membrane has potassium and calcium ion channels.
- 2. Potassium ion channels are normally open so potassium ions flow out.
- 3. When blood glucose concentration is high, the glucose moves into the cell.
- 4. Glucose is metabolised to produce ATP.
- 5. The ATP closes the potassium ion channels.
- 6. Accumulation of K+ ions alters potential difference across cell membrane - inside becomes less negative.
- 7. Change in potential difference opens the calcium ion channels.
- 8. Calcium ions cause vesicles of insulin to fuse with the cell membrane, releasing insulin by exocytosis.
- Diabetes mellitus:
- Disease where the body is no longer able to control its blood glucose concentration.
- Inability of cells to take up glucose from the blood. Can cause glucose to be excreted in the urine.
- May arise when the pancreatic beta cells fail to produce insulin or when insulin receptors become abnormal.
- Type 1 diabetes:
- (Juvenile-onset diabetes) caused by an autoimmune response where the body's own immune system attacks Beta cells and destroys them. Could also be caused by a viral infection.
- Type 2 diabetes:
- Non-insulin dependent. Insulin levels may be normal or reduced but the target cells fail to respond to the hormone due to receptor abnormalities.
- Factors that bring about earlier onset. These include: Obesity, a diet high in sugar, being of Asian or Afro-Caribbean origin, family history.
- Treatment for diabetes:
- Type 1: Insulin injections. Blood glucose concentration must be monitored and correct dose of insulin must be given to ensure glucose conc remains stable.
- Type 2: Careful monitoring and control of the diet. Matched with carbohydrate intake and use.
- May be eventually supplemented with insulin injections or drugs which slow down absorption of glucose from the digestive system.
- Glucose tolerance test:
- Involves fasting for 8 hours. Blood test to determine fasting glucose conc.
- Ingestion of glucose. Blood tests to monitor glucose conc at intervals over 2 and a half hours. Results are graphed.
- Involves fasting for 8 hours. Blood test to determine fasting glucose conc.
- Control of insulin secretion:
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