3.6 Control of blood glucose levels Flashcards
What is negative feedback ?
All changes are reversed to restore optimum conditions
What is positive feedback ?
It increases the original change in conditions, opposite of negative feedback
What is glycogenesis ?
Making glycogen from glucose removed from the blood
What is glycogenolysis ?
Breaking down stored glycogen into glucose, which can be released into the blood
What is gluconeogenesis ?
Synthesis of glucose from other molecules such as amino acids
What happens when blood glucose concentration is too high ?
1- The rise in glucose is detected by beta cells in the islets of langerhans in the pancreas.
2- Insulin is secreted by beta cells
3- Insulin travels in blood to target cells called hepatocytes (liver, fat, muscle cells)
4- Binding of insulin to the receptor cells on plasma membrane of these cells causes adenyl cyclase to convert ATP into cAMP
5- cAMP activates certain enzyme controlled reactions to stimulate opening of glucose channels.
What detects if glucose is to high ?
Beta cells in the islets of langerhans in the pancreas
How does insulin travel to target cells ?
In the blood
What are the target cells for insulin ?
Hepatocytes in liver, fat and muscle cells
What converts ATP to cAMP ?
adenyl cyclase
What is the job of cAMP ?
It stimulates certain enzyme controlled reactions in order to open glucose channels. This allows glucose to enter and be converted into glycogen or fats. This decreases levels of it in the blood
What happens when blood glucose is too low ?
1- Alpha cells in the islet of langerhans detect this and secrete glucagon
2- Glucagon action inhibits beta cell action
3- Glucagon stimulates hepatocytes to turn glycogen into glucose
4- Glucose diffuses out of hepatocytes into blood
5- Cells use fatty acids and AA for respiration instead
What does cAMP stand for ?
cyclic AMP
What is the secondary messenger adrenaline used for ?
To break down blood glucose levels
Outline the process of the secondary messenger adrenaline ?
1- Adrenaline fuses to a receptor on liver cell and this causes a change in shape of receptor on inside of membrane
2- Change of shape activates adenyl cyclase which. converts ATP to cAMP
3- cAMp changes shape and activates protein kinase enzyme which catalyses reaction of glycogen into glucose
