Control Of Blood Glucose Concentration

Question 1

What is the normal concentration of blood glucose in the blood?

Answer 1

Around 90mg per 100cm3 of blood.

Question 2

In what organ is the blood glucose concentration monitored?

Answer 2

It is monitored in the pancreas.

Question 3

Which type of cells secrete insulin?

Answer 3

ß-cells secrete insulin.

Question 4

Which cells secrete glucagon into the blood?

Answer 4

a-cells secrete glucagon into the blood.

Question 5

Which system controls blood glucose levels?

Answer 5

The hormonal system.

Question 6

From which cluster of cells in the pancreas are insulin and glucagon secreted from?

Answer 6

They are secreted from the islets of Langerhans.

Question 7

Describe how insulin lowers the concentration of glucose within the blood.

Answer 7

Insulin lowers the concentration of glucose in the blood when its too high.

1) Insulin binds to specific receptors on the cell membranes of liver and muscle cells.
2) This increases the permeability of the muscle cell membranes to glucose, therefore they take up more glucose (this involves the number of channel proteins in the membrane increasing).
3) Insulin also activates enzymes in liver and muscle cells that convert glucose to glycogen.
4) Cells can store glycogen in cytoplasm as an energy store.
5) Insulin also increases the rate of respiration of glucose in cells.

Question 8

What is the process of forming glycogen called?

Answer 8

The process is called glycogenesis.

Question 9

Describe how glucagon raises blood glucose concentration.

Answer 9

Glucagon raises blood glucose concentration when it’s too low.

1) Glucagon binds to specific receptors on the cell membranes of liver cells.
2) This activates enzymes in liver cells that break down glucagon to glucose.
3) Glucagon also activates enzymes that involved when forming glucose from glycerol and amino acids.
4) Glucagon decreases rate of respiration of glucose in cells.

Question 10

Name the process of breaking down glycogen.

Answer 10

The process of breaking down glycogen is called glycogenolysis.

Question 11

Name the process of forming glucose from non-carbohydrates.

Answer 11

The process is called gluconeogenesis.

Question 12

What is the job of GLUT4 and where is it found in the body?

Answer 12

GLUT4 is a channel protein involved in the transportation of glucose. It is found in the in skeletal and cardiac muscle cells.

Question 13

What happens when insulin levels are low?

Answer 13

GLUT4 is stored in the vesicles in the cytoplasm of cells.

Question 14

What happens when insulin binds to receptors?

Answer 14

It triggers the movement of GLUT4 to the membrane. Glucose can then be transported into the cell through the GLUT4 protein via facilitated diffusion.

Question 15

From where is adrenaline secreted?

Answer 15

The adrenal glands.

Question 16

When is adrenaline secreted?

Answer 16

When there’s a low concentration of glucose in the blood, when you’re stressed and when you’re exercising.

Question 17

What does adrenaline do?

Answer 17

It binds to receptors in the cell membrane of liver cells. It activates glycogenolysis (breakdown of glycogen to glucose) and it inhibits glycogenesis (the synthesis of glycogen from glucose).

Question 18

What does adrenaline do to Glucagon and Insulin secretion?

Answer 18

It activates Glucagon secretion and inhibits insulin secretion.

Question 19

How do adrenaline and glucagon act via a second messenger?

Answer 19

1) Adrenaline and glucagon are able to bid to their complementary receptors on the outside of the cell.
2) This activates an enzyme called adenylate cyclase.
3) Once activated this enzyme converts ATP into a chemical signal called a ‘second messenger’, which is called cyclic AMP (cAMP).
4) cAMP activates an enzyme called protein kinase A. Protein kinase activates a cascade -chain of reactions - that breaks down glycogen into glucose (glycogenolysis).

Question 20

When does diabetes occur?

Answer 20

When blood glucose concentration is not controlled.

Question 21

What is involved when a person has type 1 diabetes?

Answer 21

This is when the immune system attacks ß-cells in the islets of Langerhans so they can’t produce insulin. The cause is still unknown.

Question 22

What happens to a type 1 diabetic after eating?

Answer 22

The blood glucose levels rises and stays high - this is called hyperglycaemia. The kidneys cant reabsorb all of this glucose so some is excreted via the urea.

Question 23

How can type 1 diabetes be treated?

Answer 23

It can be treated with insulin therapy. Most people need regular insulin injections throughout the day and some people need a pump which works constantly. Levels need to be carefully controlled because too much insulin could produce a dangerous drop in blood glucose levels - hypoglycaemia.

Question 24

How can a sufferer of type 1 diabetes avoid a sudden rise on blood glucose?

Answer 24

By eating regularly and controlling your simple carbohydrate intake (sugars).

Question 25

When Is type 2 acquired?

Answer 25

Often acquired later in life. Often linked with obesity and is more likely to occur in families with a history of type 2.

Question 26

When does type 2 diabetes occur?

Answer 26

When the ß-cells don’t produce enough insulin it when the body’s cells don’t respond to insulin. Cells don’t respond to properly because the insulin receptors on their membrane don’t work properly so they don’t take up enough glucose. This means that the blood glucose levels in the blood will be high.

Question 27

Which additional health problems can be associated with type 2 diabetes?

Answer 27

These include visual impairment and kidney failure.

Question 28

What can you do to decrease your risk of getting type 2 diabetes?

Answer 28

1) have a healthy diet that’s low in fat, sugar, salt with plenty of whole grains, fruits and veg
2) exercise regularly
3) lose weight if necessary