6.4.2 Control of Blood Glucose

Question 1

What causes a rise in blood glucose

Answer 1

eating sugary food and carbohydrates

Question 2

What detects a rise in blood glucose

Answer 2

Beta cells in Islets of Langerhans in pancreas

Question 3

Response of Beta cells in Islets of Langerhans in pancreas detecting a rise in blood glucose

Answer 3

Beta cells release insulin into blood

Question 4

Describe and explain the process of insulin’s actions

Answer 4

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

Question 5

Where does insulin bind

Answer 5

Receptors on cell-surface membrane of target cells (liver+ muscle cells)

Question 6

What are the three ways in which insulin lowers the blood glucose levels

Answer 6

• Causes change in tertiary structure of glucose carrier proteins, allowing more glucose to enter cell by faccilitated diffusion
• Causes vesicles containing glucose carrier proteins to fuse with cell-surface membrane, allowing more glucose to enter cell by facilitated diffusion
• Activates enzymes involved in glycogenesis (glucose –> glycogen)

Question 7

What causes a fall in blood glucose

Answer 7

Exercise and not eating sugar food/carbohydrates

Question 8

What detects fall in blood glucose

Answer 8

Alpha cells in Islets of Langerhans in pancreas

Question 9

Response of fall in blood glucose concentration detected by alpha cells in Islets of Langerhans in pancreas

Answer 9

Alpha cells release glucagon into blood

Question 10

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

Answer 10

• 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)
• Facilitated diffusion of glucose out of liver + muscle cells
• Blood glucose levels increase

Question 11

What is glycogenesis

Answer 11

glucose to glycogen

Question 12

Process of glucose to glycogen

Answer 12

Glycogenesis

Question 13

What is glycogenolysis

Answer 13

Hydrolysis of glycogen to glucose

Question 14

What is gluconeogenesis

Answer 14

Synthesis of glucose from glycerol and amino-acid

Question 15

Process of synthesis of glucose from glycerol and amino-acids

Answer 15

Gluconeogenesis

Question 16

Process of hydrolysis of glycogen to glucose

Answer 16

Glycogenolysis

Question 17

Describe and explain the actions of adrenaline in lowering blood glucose concentration (not secondary messenger model)

Answer 17

• 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)
• Facilitated diffusion of glucose out of liver + muscle cells
• Blood glucose levels increase

Question 17

What hormones increase blood glucose levels

Answer 17

Glucagon + adrenaline

Question 18

Describe and explain the secondary messenger model for increasing blood glucose concentration

Answer 18

• Glucoagon or adrenaline binds to glycoprotein receptor on cell-surface membrane of target cells (liver + muscle cells)
• Causes change in tertiary strucutre of adenylate cyclase, activating the enzyme
• Activated adenylate cyclase catalyses the conversion of ATP to cyclic AMP (cAMP)
• cAMP acts as secondary messenger
• cAMP diffuses through cytoplasm, binding to enzyme kinase
• Causes change in tertiary structure, activating it
• Activated kinase catalyses hydrolysis of glycogen to glucose (glycogenolysis)

Question 19

List the order of molecules involved in the secondary messenger model

Answer 19

• Glucagon / adrenaline
• Adenylate cyclase
• ATP
• cAMP
• Kinase

Question 20

What molecule acts as the secondary messenger when increasing blood glucose

Answer 20

cAMP

Question 21

What does cAMP bind to, to activate it

Answer 21

Kinase

Question 22

What does activated adenylate cyclase catalyse

Answer 22

Conversion of ATP to cAMP

Question 23

In the secondary mesenger model, what does the binding of glucagon/adrenaline to receptors on cell-surface membrane of target cells (liver and muscle cells) cause

Answer 23

Change in tertiary structure of adenylate cyclase, activating the enzyme

Question 24

How does type 1 diabeties affect people

Answer 24

Insulin is **not produced**

Question 25

How can type 1 diabeties be controlled

Answer 25

* Insulin injections * Control of diet

Question 26

How does type 2 diabeties affect people

Answer 26

* Insulin still produced * Glycoprotein receptors **less sensitive to insulin**

Question 27

How can type 2 diabeties be controlled

Answer 27

* Control of exercise * Control of diet