3.6.4.2 Control of blood glucose concentration – AQA A Level Biology Summary Notes
Factors that influence blood glucose concentration
- Glucoregulation = negative feedback
Raise blood glucose Reduce blood glucose
Eating, digesting and absorbing Exercise – muscles respire rapidly so
carbohydrates (simple and complex) blood glucose level falls more quickly
Glucagon (hormone releases glucose from Insulin (hormone causes glucose to enter
glycogen stores) cells more rapidly and be stored as
glycogen)
Adrenaline (causes release of glucose)
Note: eating disaccharides will result in a quicker increase in blood glucose concentration
than eating polysaccharides due to smaller number of steps in digestion
The role of the liver in glycogenesis, glycogenolysis and gluconeogenesis
Pancreas makes and secretes the hormones glucagon and insulin
- Means pancreas has an endocrine function
Also has an exocrine function as enzymes are secreted via a duct into the small intestine
Note: endocrine tissue is surrounded by exocrine tissue
Alpha cells of pancreas release GLUCAGON (larger and lighter)
Beta cells of pancreas release INSULIN (smaller and darker)
Insulin
- Secreted by Beta cells of pancreas when blood glucose concentration is too high
- Causes a decrease in blood glucose concentration
- Acts only on target cells: muscle and liver cells (hepatocytes), which have
complementary receptors on cell surface membranes
Action of insulin
1) Insulin binds to specific complementary receptors on surfaces of target cells
(muscle/liver)
2) Controlling uptake of glucose by regulating inclusion of GLUT4 protien channels in
surface membrane of target cells
3) Glucose enters (cells) from blood by facilitated diffusion
4) Glucose either converted to glycogen by glycogenesis by enzymes OR converted to
fatty acids for storage
5) Insulin leads to higher metabolic rate in target cells (more respiration, more glucose
used up in glycolysis)
Factors that influence blood glucose concentration
- Glucoregulation = negative feedback
Raise blood glucose Reduce blood glucose
Eating, digesting and absorbing Exercise – muscles respire rapidly so
carbohydrates (simple and complex) blood glucose level falls more quickly
Glucagon (hormone releases glucose from Insulin (hormone causes glucose to enter
glycogen stores) cells more rapidly and be stored as
glycogen)
Adrenaline (causes release of glucose)
Note: eating disaccharides will result in a quicker increase in blood glucose concentration
than eating polysaccharides due to smaller number of steps in digestion
The role of the liver in glycogenesis, glycogenolysis and gluconeogenesis
Pancreas makes and secretes the hormones glucagon and insulin
- Means pancreas has an endocrine function
Also has an exocrine function as enzymes are secreted via a duct into the small intestine
Note: endocrine tissue is surrounded by exocrine tissue
Alpha cells of pancreas release GLUCAGON (larger and lighter)
Beta cells of pancreas release INSULIN (smaller and darker)
Insulin
- Secreted by Beta cells of pancreas when blood glucose concentration is too high
- Causes a decrease in blood glucose concentration
- Acts only on target cells: muscle and liver cells (hepatocytes), which have
complementary receptors on cell surface membranes
Action of insulin
1) Insulin binds to specific complementary receptors on surfaces of target cells
(muscle/liver)
2) Controlling uptake of glucose by regulating inclusion of GLUT4 protien channels in
surface membrane of target cells
3) Glucose enters (cells) from blood by facilitated diffusion
4) Glucose either converted to glycogen by glycogenesis by enzymes OR converted to
fatty acids for storage
5) Insulin leads to higher metabolic rate in target cells (more respiration, more glucose
used up in glycolysis)
