Regulation of Blood Glucose

Question 1

Where is insulin stored?

Answer 1

-beta cells

Question 2

How do hormones work?

Answer 2

-carried in blood plasma to target cells
-complementary receptors

Question 3

What hormones follow the second messenger mode of action?

Answer 3

-adrenaline + glucagon

Question 4

What happens during the resting state?

Answer 4

-90mg normal glucose level
-K channels in beta cells open
-K diffuses out
-inside is now -70mv compared to outside

Question 5

What happens during detection?

Answer 5

-glucose conc increases
-glucose enters by a transporter
-then metabolised in mitochondria = ATP
-ATP binds to K channels = close
-K no longer diffuses out = depolarisation
-causes Ca channels to open - floods in
-vesicles with insulin to release it through exocytosis

Question 6

Where is glucagon stored?

Answer 6

-alpha cells

Question 7

What are the 3 natural sources of blood glucose?

Answer 7

1. directly from diet
2. breakdown of glycogen
3. gluconeogenesis

Question 8

What do beta cells detect?

Answer 8

-exceptions for a rise in blood levels
-when detected they secrete insulin

Question 9

What happens when insulin is secreted into the blood?

Answer 9

-binds to glycoprotein receptors on cell surface of most body cells

Question 10

How can you reduce blood glucose levels?

Answer 10

1. more glucose absorbed into cells
2. increases respiratory rate of cells so more glucose is used up
3. increasing rate of glycogenesis
4. increasing conversion of glucose to fat

Question 11

How can you increase blood glucose levels?

Answer 11

-act as receptors that detect fall in blood glucose
-when detected - secrete glucagon into blood
-glucagon binds to glycoprotein receptors on LIVER CELLS

Question 12

Why is it important to maintain a normal BGL?

Answer 12

-BGL could affect WP grad between cells + blood
-too high = water leaves = dehydration
-too low = water enters = burst
-may disrupt conc of other chemicals in other cells

Question 13

When does BGL increase?

Answer 13

-ingestion of food or drink containing carbs

Question 14

When does BGL decrease?

Answer 14

-following exercise of if you haven’t eaten

Question 15

What is the action of insulin?

Answer 15

1. attaches to receptors on surface of target cells - changes tertiary structure = more glucose absorbed
2. more channels are incorporated = more glucose absorbed from blood into cells
3. activating enzymes used in conversion of glucose to glycogen (glycogenesis)

Question 16

What is the action of glucagon?

Answer 16

1. attaches to receptors on surface of target cells
2. when it binds = protein activated into adenylate cyclase
3. converts ATP into cAMP which activates kinase that can hydrolyse glycogen into glucose
4. activating enzymes involved in conversion of glycerol + amino acids into glucose

Question 17

How does adrenaline increase BGL?

Answer 17

1. attaches to receptors - causes G protein to be activated + convert ATP to cAMP
2. cAMP activates enzyme that hydrolyses glycogen into glucose
3. known as second messenger model

Question 18

Why is there a delay in the increase of insulin concentration following the increase in blood glucose concentration?

Answer 18

-increase in blood glucose detected by beta cells
-takes time