W3-L2: Glucose Metabolism

Question 1

What are the 3 fates of Glucose Metabolism?

Answer 1

Question 2

What are the Hormones involved in Blood Glucose Metabolism? (5)

Answer 2

Released by the Adrenal Gland:
- Epinephrine
- Norepinephrine
- Cortisol

Released by the Pancreas
- Glucagon
- Insulin

Question 3

What is the effect of Epinephrine on Blood Glucose Levels?

Answer 3

• Activates Gluconeogenesis & Glycogenolysis
• Increases Blood Glucose

Question 4

What is the effect of Norepinephrine on Blood Glucose Levels?

Answer 4

• Activates glycogenolysis
• Increases Blood Glucose

Question 5

What is the effect of Cortisol on Blood Glucose Levels?

Answer 5

• Activates Gluconeogenesis
• Sustains Blood Glucose Levels

Question 6

What is the effect of Glucagon on Blood Glucose Levels?

Answer 6

• Activates gluconeogenesis & glycogenolysis
• Increases Blood Glucose

Question 7

What is the effect of Insulin on Blood Glucose Levels?

Answer 7

• Activates glycolysis & glycogen synthesis
• Decreases Blood Glucose

Question 8

What is Glycogenesis?

Answer 8

Glucose molecules are branched together to form glycogen

Question 9

What is Glycogenolysis?

Answer 9

Breakdown of glycogen into glucose

Question 10

What are Gluconeogenesis?

Answer 10

Creating glucose from non carbohydrate precursors
e.g. glycerol and amino acids

Question 11

What is Glycolysis?

Answer 11

Breakdown of glucose into 2 x pyruvate

Question 12

What is Lipolysis?

Answer 12

breakdown of triglycerides into glycerol and fatty acids in the mitochondria

Question 13

What is Beta oxidation?

Answer 13

breakdown of fatty acids into acetyl-CoA for entry into the Krebs cycle

Question 14

What is Lipogenesis?

Answer 14

Excess acetyl Co-A is converted to fatty acid chains

Question 15

What is normal Blood Glucose level?
What happens to it after eating carbs?

Answer 15

• Blood glucose is normally maintained within the range of 3.9 – 5.5mmol/L (70 to100 mg/dl) under fasting conditions
• Will rise after a meal containing carbohydrates – approx. 7mmol/L
• Blood glucose levels usually return to resting level between 30 and 120 min after eating has finished

Glucose impairment is associated with diabetes mellitus, suspected when fasting blood glucose levels exceed 7mmol/L (126 mg/dl)

Question 16

What is the purpsoe of GLUT 4 Receptors?

Answer 16

Question 17

What is average Blood Glycogen Levels:
In the Blood?
In Skeletal Muscle?
In the Liver?

Answer 17

• Blood (4-5g glucose)
• Skeletal muscle (approx. 300 - 400g)
• Liver (75 – 100g)

Question 18

What triggers Glycogenesis?

Answer 18

Glycogenesis: assembles glucose molecules into branched chains for storage as glycogen

• Triggered by rest (post activity) and consumption of carbohydrates (increasing insulin)

Question 19

What is the Rate limiting enzyme in Glycogenesis?

Answer 19

Rate limiting enzyme = glycogen synthase

Question 20

How is the storage of glycogen related to the term “water weight”?

Answer 20

Every 1g of glycogen is stored w/ approx. 3g water

Question 21

What is the difference b/w Liver & Muscle Glycogen?

Answer 21

Liver glycogen – glucose reserve for blood
* Depleted after an overnight fast
Muscle glycogen – glucose reserve for muscle (cannot be released into the blood)

Question 22

What level of excersize do Glycogen stores support?

Answer 22

Glycogen stores will support:

moderate intensity exercise for 90 mins or

high intensity exercise for approximately 30 - 45 mins

Question 23

What hormones trigger Glycogenolysis?

Answer 23

Glucagon, norepinephrine and epinephrine

Question 24

What happens to Lipogenesis during times of excess calorie consumption?

Answer 24

• Lipogenesis: Excess Acetyl Co-A is converted to fatty acid chains in the cytosol
• Biosynthetic pathway accelerated during times of excess calorie consumption

Question 25

What is the key hormone in stimulating lipogenesis?

Answer 25

• Insulin is a key hormone in stimulating lipogenesis – Insulin
  promotes the activity of enzymes involved in fatty acid synthesis and inhibits the breakdown of fat by inhibiting lipases

Question 26

What is the function of lipoprotein lipase?

Answer 26

• During lipogenesis surplus fatty acids are combined with glycerol to form triglycerides
• Adipose tissue releases lipoprotein lipase which breaks down triglycerides in circulating lipoproteins, releasing fatty acids which are then taken up for storage in the adipocyte