Control of blood glucose concentration

Question 1

What are factors that affect blood glucose concentration

Answer 1

-eating food containing carbohydrates → glucose absorbed into intestine from blood
-exercise → increases rate of respiration (lower blood glucose concentration)

Question 2

Where is insulin produced?

Answer 2

by beta cells in islets of Langerhans in pancreas

Question 3

When is insulin released?

Answer 3

when blood glucose levels are too high

Question 4

How does insulin work?

Answer 4

1) binds to specific receptors on target cells (e.g. muscle or liver cells)
2) increases cell membrane permeability to glucose by increasing number of channel proteins (GLUT4) → cells uptake more glucose by facilitated diffusion
3) activates enzymes in the target cell to convert glucose → glycogen (glycogenesis)
DECREASES blood glucose concentration

Question 5

Where is glucagon secreted?

Answer 5

by alpha cells in the islets of Langerhans in pancreas

Question 6

When is glucagon secreted?

Answer 6

when blood glucose concentration is too low

Question 7

How does glucagon work?

Answer 7

1) secreted by alpha cells in islets of langerhans in pancreas when BGC low
2) binds to specific receptors on target cells
3) activates enzymes in the conversion of glucagon → glucose (glycogenolysis)
4) activates enzymes in the conversion of amino acids → glucose (gluconeogenesis)

Question 8

Glycogenolysis

Answer 8

glycogen → glucose

Question 9

Glycogenesis

Answer 9

glucose → glycogen

Question 10

Gluconeogenesis

Answer 10

amino acids → glucose

Question 11

Where is adrenaline secreted from?

Answer 11

adrenal glands

Question 12

When is adrenaline secreted

Answer 12

when blood glucose concentration is too low

Question 13

How does adrenaline work?

Answer 13

1) secreted by adrenal glands when BGC too low
2) binds to specific receptors on target cells
3) activates enzymes in the conversion of glycogen to glucose (glycogenolysis)
- inhibits glycogenesis
4) activates secretion of glucagon
5) INCREASES blood glucose concentration

Question 14

How does the secondary messenger model work?

Answer 14

1) adrenaline/glucagon bind to specific complementary receptors on cell membrane
2) activates adenylate cyclades
3) converts ATP into cAMP (secondary messenger)
4) cAMP activates protein kinase A (enzyme)
5) protein kinase A activates a cascade to break down glycogen → glucose (glycogenolysis)

Question 15

Diabetes

Answer 15

blood glucose concentration cannot be controlled properly. BGC remains high after meals and takes longer to decrease

Question 16

What’s the cause of type 1 diabetes?

Answer 16

gene mutation → causes immune system to attack b-cells on islets on langerhans → body can’t produce insulin

Question 17

How do you control type 1 diabetes? (insulin)

Answer 17

• Injection of insulin (not by mouth as protein is digested)
• dose of insulin matched with glucose intake using biosensors

Question 18

How do you control type 1 diabetes? (diet manipulation)

Answer 18

• eat regularly, control carb intake e.g. carbs that are broken down/absorbed slower

Question 19

What’s the cause of type 2 diabetes

Answer 19

• poor diet/ lack of exercise/ obesity
• body’s cells don’t respond to insulin as receptors on their membrane doesn’t work
• so cells don’t uptake enough glucose

Question 20

How do you control type 2 diabetes? (insulin)

Answer 20

• use of drugs which target insulin receptors
• more glucose uptake by cells
  DECREASES blood glucose concentration

Question 21

How do you control type 2 diabetes? (diet manipulation)

Answer 21

• Reduce sugar intake (carbs) in diet
  → less sugar absorbed into blood
• Regular exercise
  → uses glucose for respiration
• Reduce fat intake
  →less fat is converted to glucose