6.4.2 Control of Blood Glucose

Question 1

What causes a rise in blood glucose concentration

Answer 1

Eating sugary food or carbohydrates

Question 2

What detects an increase in blood glucose concentration, and what is the response

Answer 2

• Detected by beta cells in Islets of Langerhans in pancreas
• Beta cells release insulin into blood

Question 3

Describe and explain the actions of insulin in lowering blood glucose concentration

Answer 3

• Binds to glycoprotein receptors on cell-surface membrane of target (liver + muscle) cells
• Causes change in tertiary structure of glucose carrier proteins, allowing more glucose to enter cell by facillitated diffusion
• Also causes more vesicles containing carrier protiens to fuse with cell-surface membrane, allowing more glucose to enter cell by faccilitated diffusion
• Activates enzymes involved in glycogenesis (glucose –> glycogen)

Question 4

What is glycogeneis

Answer 4

Glucose –> glycogen

Question 5

What causes a fall in blood glucose concentration

Answer 5

Exercise, and not eating carbohydrates

Question 6

What detects the fall in blood glucose concentration, and what is the effect

Answer 6

• Detected by alpha cells in Islets of Langerhans in pancreas
• Alpha cells release glucagon into blood

Question 7

Describe and explain the actions of glucagon in increasing blood glucose concentration

Answer 7

• Binds to glycoprotein receptors on cell-surface membrane of target cells (liver+muscle) cells
• Activates enzymes involved in glycogenolysis (hydrolysis of glycogen to glucose)
• Activates enzymes involved in gluconeogenesis (synthesis of glucose from glycerol and amino-acids)
• Faccilitated diffusion of glucose out of liver and muscle cells

Question 8

What is gluconeogenesis

Answer 8

Synthesis of glucose from glycerol and amino-acids

Question 9

What is glycogenolysis

Answer 9

Hydrolysis of glycogen to glucose