Control of blood glucose concentration Flashcards
What are factors that affect blood glucose concentration
-eating food containing carbohydrates → glucose absorbed into intestine from blood
-exercise → increases rate of respiration (lower blood glucose concentration)
Where is insulin produced?
by beta cells in islets of Langerhans in pancreas
When is insulin released?
when blood glucose levels are too high
How does insulin work?
1) binds to specific receptors on target cells (e.g. muscle or liver cells)
2) increases cell membrane permeability to glucose by increasing number of channel proteins (GLUT4) → cells uptake more glucose by facilitated diffusion
3) activates enzymes in the target cell to convert glucose → glycogen (glycogenolysis )
DECREASES blood glucose concentration
Where is glucagon secreted?
by alpha cells in the islets of Langerhans in pancreas
When is glucagon secreted?
when blood glucose concentration is too low
How does glucagon work?
1) secreted by alpha cells in islets of langerhans in pancreas when BGC low
2) binds to specific receptors on target cells
3) activates enzymes in the conversion of glucagon → glucose (glycogenolysis)
4) activates enzymes in the conversion of amino acids → glucose (gluconeogenesis)
Glycogenolysis
glycogen → glucose
Glycogenesis
glucose → glycogen
Gluconeogenesis
amino acids → glucose
Where is adrenaline secreted from?
adrenal glands
When is adrenaline secreted
when blood glucose concentration is too low
How does adrenaline work?
1) secreted by adrenal glands when BGC too low
2) binds to specific receptors on target cells
3) activates enzymes in the conversion of glycogen to glucose (glycogenolysis)
- inhibits glycogenesis
4) activates secretion of glucagon
5) INCREASES blood glucose concentration
How does the secondary messenger model work?
1) adrenaline/glucagon bind to specific complementary receptors on cell membrane
2) activates adenylate cyclades
3) converts ATP into cAMP (secondary messenger)
4) cAMP activates protein kinase A (enzyme)
5) protein kinase A activates a cascade to break down glycogen → glucose (glycogenolysis)
Diabetes
blood glucose concentration cannot be controlled properly. BGC remains high after meals and takes longer to decrease
What’s the cause of type 1 diabetes?
gene mutation → causes immune system to attack b-cells on islets on langerhans → body can’t produce insulin
How do you control type 1 diabetes? (insulin)
- Injection of insulin (not by mouth as protein is digested)
- dose of insulin matched with glucose intake using biosensors
How do you control type 1 diabetes? (diet manipulation)
- eat regularly, control carb intake e.g. carbs that are broken down/absorbed slower
What’s the cause of type 2 diabetes
- poor diet/ lack of exercise/ obesity
- body’s cells don’t respond to insulin as receptors on their membrane doesn’t work
- so cells don’t uptake enough glucose
How do you control type 2 diabetes? (insulin)
- use of drugs which target insulin receptors
- more glucose uptake by cells
DECREASES blood glucose concentration
How do you control type 2 diabetes? (diet manipulation)
- Reduce sugar intake (carbs) in diet
→ less sugar absorbed into blood - Regular exercise
→ uses glucose for respiration - Reduce fat intake
→less fat is converted to glucose
