6- Control of Blood glucose =)

Question 1

Describe the role of glucagon in gluconeogenesis.
Do not include in your answer details on the second messenger model of glucagon action. (2)

Answer 1

• attaches to receptors on target cells –> activates enzymes
• making glucose from a.a./ fatty acids/ glycerol

Question 2

Explain how increasing a cell’s sensitivity to insulin will lower the blood glucose concentration. (2)

Answer 2

• ↑ insulin binds to receptors
• ↑ uptake of glucose by channel proteins

Question 3

Explain how inhibiting adenylate cyclase may help to lower the blood glucose concentration. (3)

Answer 3

• ↓ ATP converted to cAMP
• ↓ glycogen –> glucose// ↓ glyuconeogenesis

Question 4

Using your knowledge of the kidney, explain why glucose is found in the urine of a person with untreated diabetes. (3)

Answer 4

• high blood glucose conc
• x all reabsorbed at proximal convoluted tubule
• carrier proteins saturated /working at max rate

Question 5

Give two reasons why pancreas transplants are not used for the treatment of type II diabetes. (2)

Answer 5

1. type II diabetics ✔ produce insulin
2. cells x respond to insulin// faulty insulin receptors
3. treated by exerecise/ diet

Question 6

Scientists investigated the control of blood glucose concentration in mice. They kept a group
of normal mice without food for 48 hours. After 48 hours, the blood glucose concentrations of the mice were the same as at the start of the experiment.
Explain how the normal mice prevented their blood glucose concentration falling
when they had not eaten for 48 hours. (3)

Answer 6

• glucagon released
• formation of glucose in liver cells
• from a.a./ f.a.

Question 7

When insulin binds to receptors on liver cells, it leads to the formation of glycogen from glucose. This lowers the concentration of glucose in liver cells.
Explain how the formation of glycogen in liver cells leads to a lowering of blood glucose concentration. (2)

Answer 7

• glucose conc in cell falls below that in blood –> glucose conc gradient
• glucose enters cells from blood by f. diffusion thru carrier proteins

Question 8

Adrenaline binds to recpetors in the plasma membranes of liver cells.
Explain how this causes blood glucose concentration to increase. (2)

Answer 8

1. adenylate cyclase activated - ATP –> cyclic AMP
2. activates enzymes in cell –> glycogenolysis (glycogen –> glucose)

Question 9

What is the storage compound made from excess blood glucose? (1)

Answer 9

fats/ lipid