Control of Blood Glucose Concentraiton

Question 1

what happens when theres an increase in blood glucose concentration

Answer 1

• beta cells in the pancreas secrete the hormone insulin into the bloodstream

Question 2

how does insulin decrease the blood glucose concentration

Answer 2

• insulin attaches to specific receptors on the surface of the target cells e.g. liver and muscle cells
• this increases the permeability of the target cells to glucose by stimulating the inclusion of more specific channel proteins in the membrane which allow glucose to diffuse in , deceasing the concentration of glucose in the blood
• glycogenesis - insulin also activates enzymes in the liver that convert glucose into glycogen

Question 3

what happens when glycogen stores are full

Answer 3

• excess glucose is converted to fat

Question 4

what happens when there is a decrease in blood glucose

Answer 4

• alpha cells in the pancreas secrete the hormone glucagon into the blood

Question 5

how does glucagon increase the blood glucose concentration

Answer 5

• glycogenolysis - glucagon attaches to specific receptors on the surface of target cells of the liver and activates enzymes which hydrolyse glycogen into glucose which is then released into the blood

Question 6

what happens when the demand for glucose exceeds the glycogen stored in the liver

Answer 6

• gluconeogenesis - glucagon activates enzymes which convert glycerol and amino acids into glucose which is released into the blood

Question 7

what is adrenaline

Answer 7

• a hormone released by the adrenal glands when the blood glucose concentration is low, particularly during exercise or in response to stress

Question 8

how does adrenaline increase blood glucose concentration

Answer 8

• adrenaline attaches to the receptors on the surface of specific target cells e.g. liver and muscle cells and activates enzymes that hydrolyse glycogen into glucose (glycogenolysis)
• the glucose is released into the blood to provide glucose to cells for respiration and to increase blood glucose back to normal

Question 9

describe the second messenger model of adrenaline and glucagon

Answer 9

• hormones such as adrenaline and glucagon bind to surface receptors of the target cells
• this activates the membrane-bound enzyme adenyl cyclase to convert ATP to cyclic AMP
• Cyclic AMP then activates the enzyme protein kinase which stimulates the hydrolysis of glycogen to glucose and the glucose is released into the blood to increase blood glucose and supply cells with glucose for respiration

Question 10

describe the two types of diabetes

Answer 10

• type 1 diabetes - cells in the pancreas responsible for the production of insulin are destroyed by the immune system leading to no production of insulin at all
• type 2 diabetes - cells have fewer or faulty insulin receptors and no longer respond to insulin and therefore take up less glucose therefore the blood glucose concentration remains high

Question 11

what is a significant risk factor for type 2 diabetes

Answer 11

• long term obesity

Question 12

what is a significant risk factor for type 2 diabetes

Answer 12

• long term obesity

Question 13

how are the two types of diabetes managed

Answer 13

• type 1 diabetes - they are insulin dependent and must inject themselves with insulin daily
• type 2 diabetes - control their blood glucose concentration by avoiding foods that cause a large spike in blood glucose and by regular exercise