Regulation of blood glucose and diabetes

Question 1

How do hormones act on cells?

Answer 1

They are carried in the blood plasma to the cells on which they act known as target cells- they have receptors on their surface which the hormones bind to as they are complementary to each other.

Question 2

What is the second messenger model?

Answer 2

This mechanism is used by two hormones involved in the regulation of blood glucose - adrenaline and glucagon

Question 3

How does the second messenger model work?

Answer 3

1. The hormone is the first messenger and binds to specific receptors of target cells to form a hormone-receptor complex ( adrenaline binds to receptor site)
2. The hormone receptor-complex produced then activates an enzyme inside the cell which results in the production of a chemical, this acts as the second messenger. (once adrenaline has fused with receptor an enzyme is activated inside the membrane)
3. The second messenger causes a series of chemical changes that produces the required response (the activated enzyme converts ATP- cyclic AMP which acts as a second messenger and activates other enzymes to convert glycogen-glucose)

Question 4

What is the role of the pancreas?

Answer 4

Produces enzymes and hormones for blood glucose regulation

Question 5

What are the groups of hormone-producing cells in the pancreas called?

Answer 5

Islets of Langerhans

Question 6

What are the two types of Islets of Langerhans?

Answer 6

a cells- large and produce the hormone glucagon

b cells- small and produce the hormone insulin

Question 7

Why must blood glucose levels be controlled?

Answer 7

Cells will become deprived of energy and die if levels are too low
Lowers water potential of blood and cause osmotic problems if levels are too high

Question 8

What are the three sources of blood glucose?

Answer 8

1. Directly from the diet- breakdown of carbohydrates results in glucose
2. Breakdown of glycogen- excess glucose converted into glycogen
3. Gluconeogenesis- production of new glucose from sources such as the liver that can make glucose from glycerol and amino acids

Question 9

What are the three main hormones involved in blood glucose regulation?

Answer 9

Glucagon, Insulin and Adrenaline

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Question 10

How does b cells of the pancreas and insulin lower glucose levels?

Answer 10

b cells detect a rise in blood glucose levels and respond by secreting insulin directly into the blood plasma.

Question 11

What happens when a body cell combines with insulin molecules?

Answer 11

• Change in glucose transport chains tertiary structure so that more glucose enters cells
• Increase in number of carrier molecules on cell-surface membranes
• Activation of enzymes that convert glucose - glycogen and fat

Question 12

How does insulin lower glucose levels?

Answer 12

• Increases the rate of absorption of glucose into cells
• Increases respiratory rate of cells so that they take up more glucose from the blood
• Increases rate of conversion of glucose-glycogen
• Increases rate of conversion of glucose-fat

Question 13

What is the lowering of blood glucose level causing the secretion of insulin to be reduced by b cells an example of?

Answer 13

Negative feedback

Question 14

How do a cells and glucagon increase blood glucose levels?

Answer 14

a cells detect a fall in blood glucose levels and respond by secreting glucagon directly into the blood plasma - only in liver cells as these only have the receptors which are able to bind to glucagon

Question 15

What happens when glucagon binds to a liver cell?

Answer 15

• Activates an enzyme to convert glycogen-glucose

- Increases the conversion of amino acids and glycerol into glucose

Question 16

What is the raising of blood glucose level causing the secretion of glucagon to be lowered by a cells an example of?

Answer 16

Negative feedback

Question 17

How does adrenaline increase blood glucose levels?

Answer 17

• Activates an enzyme that causes the breakdown of glycogen to glucose in the liver
• Inactivating the enzyme that synthesises glycogen from glucose

Question 18

How do the hormones insulin and glucagon work antagonistically?

Answer 18

Insulin lowers blood glucose levels whereas glucagon increases it - means levels fluctuate around a set point that doesn’t allow levels to get too high or too low

Question 19

What is diabetes?

Answer 19

Metabolic disorder caused by an inability to control blood glucose levels due to a lack of the hormone insulin or a loss of responsiveness to insulin

Question 20

What is Type 1 diabetes?

Answer 20

This is where the body cant produce insulin - due to body producing an immune response to its own b cells in pancreas

Question 21

What is Type 2 diabetes?

Answer 21

This is where the glycoprotein receptors on body cells lose their responsiveness to insulin or an inadequate supply from the pancreas. Due to obesity

Question 22

How is Type 1 diabetes controlled?

Answer 22

Injections of insulin.

Must manage carbohydrate intake as dose of insulin must match glucose intake

Question 23

How is Type 2 diabetes controlled?

Answer 23

Regulating the intake of carbohydrates and exercise.

Maybe supplemented by injections of insulin or drugs that slow the absorption of glucose from the intestine