BGM1002/L26 Control of Glucose & Glycogen Metabolism

Question 1

What happens to glycogen metabolism in muscles during exercise?

Answer 1

Increased glycolysis
Increased glucose uptake
Increased glycogen breakdown
Decreased glycogen synthesis

Question 2

What happens to glycogen metabolism in muscles at rest?

Answer 2

Decreased glycolysis
Decreased glucose uptake
Decreased glycogen breakdown
Increased glycogen synthesis

Question 3

What happens to glycogen metabolism in the liver after a meal?

Answer 3

Decreased glucose release
Decreased glycogen breakdown
Increased glycogen synthesis

Question 4

What happens to glycogen metabolism in the liver during fasting/exercise?

Answer 4

Increased glucose release
Increased glycogen breakdown
Decreased glycogen synthesis

Question 5

What 3 key hormones regulate glycogen metabolism?

Answer 5

Epinephrine
Glucagon
Insulin

Question 6

Where is epinephrine released from?

Answer 6

Adrenal medulla

Question 7

Where are glucagon and insulin released from?

Answer 7

Pancreas

Question 8

What mechanism does epinephrine act through to affect glycogen metabolism?

Answer 8

G-protein linked receptors

Question 9

What cascade of events does epinephrine cause in glycogen metabolism?

Answer 9

cAMP-dependent phosphorylation cascade

Question 10

Where does epinephrine act to affect glycogen metabolism?

Answer 10

Muscle and liver

Question 11

What hormone is secreted by beta cells?

Answer 11

Insulin

Question 12

What hormone is released by alpha cells?

Answer 12

Glucagon

Question 13

What other kinds of cells does the pancreas contain?

Answer 13

Delta cells (somatostatin), PP cells and others

Question 14

Why is the pancreas highly vascularised?

Answer 14

For glucose sensing and high O2/nutrient demand

Question 15

What percentage by mass of the pancreas are islet cells?
What percentage blood flow of the pancreas do they require?

Answer 15

1-2% mass
10-15% blood supply

Question 16

What tissue does glucagon act on?

Answer 16

Liver

Question 17

What tissues does insulin act on?

Answer 17

Liver and muscle cells
Adipose tissue

Question 18

Name 2 key enzymes in control of glycogen metabolism.

Answer 18

Glycogen phosphorylase
Glycogen synthase

Question 19

How is glycogen phosphorylase activated?

Answer 19

Phosphorylation

Question 20

How is glycogen synthase activated?

Answer 20

Removal of phosphate group

Question 21

Which 2 key hormones in glycogen metabolism act via G-protein linked receptor?

Answer 21

Glucagon and epinephrine

Question 22

By what mechanism does insulin work?

Answer 22

Via a receptor tyrosine kinase

Question 23

How many isoforms of GLUT transporters exist?

Answer 23

16

Question 24

Where are GLUT1 and GLUT3 found?

Answer 24

All mammalian tissues

Question 25

Where are GLUT2 found?

Answer 25

Liver and pancreatic beta-cells

Question 26

What is the Km of GLUT1 and GLUT3 transporters?

Answer 26

1mM

Question 27

What is the Km of GLUT2 transporters?

Answer 27

15-20mM

Question 28

What is the role of GLUT2 transporters in (a) the liver and (b) in the pancreas?

Answer 28

(a) removes excess glucose from blood (b) regulation of insulin

Question 29

When blood glucose is high, how do GLUT2 transporters mediate insulin secretion? (5)

Answer 29

Glucose enters cell Glycolysis occurs Ca2+ activated Ca2+ enter cell Insulin secreted

Question 30

How does insulin affect transport of GLUT4 transporters?

Answer 30

Insulin stimulates transport of GLUT4 to plasma membrane in muscle and adipose cells

Question 31

What is the Km of GLUT4 transporters?

Answer 31

5mM

Question 32

How can number of insulin receptors be increased in muscle?

Answer 32

Endurance training

Question 33

What is type 1 diabetes mellitus?

Answer 33

Absolute insulin deficiency due to beta-cell destruction

Question 34

How is type 1 diabetes mellitus treated?

Answer 34

Exogenous insulin injection, pancreas/islet transplant

Question 35

Give 2 potential future treatments for type 1 diabetes mellitus.

Answer 35

Xenotransplantation, iPS/ePS stem cells, immunomodulation

Question 36

Name the 2 stages that type 2 diabetes WAS considered to have.

Answer 36

1 - hypeinsulinemia/beta cell compensation/peripheral insulin resistance 2 - insulin deficiency caused by beta-cell death

Question 37

Give the revised progression of type 2 diabetes.

Answer 37

1 - no change 2 - beta-cell 'hideaway' to avoid cell death

Question 38

What occurs during hyperglycaemia to cause polydipsia?

Answer 38

Glucose enters renal filtrate Glucose reabsorption saturated Water follows by osmosis Large volume of urine