Lecture 33 - Fuel mobilisation

Question 1

What is fuel mobilisation

Answer 1

Fuel molilisation is the process of breaking down stored macronutrients (carbohydrate, fats, proteins) to meet the body’s energy demands during fasting, stress, or physical activity

Question 2

Carbohydrates - fuel mobilisation

Answer 2

For carbohydrates, the process of glycogenolysis is activated to obtain glucose for glycolysis

Question 3

Fats - Fuel mobilisation

Answer 3

Lipolysis is activated to obtain FAs for B-oxidation

Question 4

Proteins - fuel mobilisation

Answer 4

Proteolysis to obtain amino acids for energy

Question 5

What is glycogenolysis

Answer 5

Glycogenolysis is the process of breaking down of glycogen into glucose, which can be used for glycolysis to produce energy

Question 6

What is lipolysis

Answer 6

Lipolysis is the breakdown of TAGs in adipose tissue to release free fatty acids and glycerol production through B oxidation

Question 7

How hormone trigger glycogenolysis in liver

Answer 7

Glucagon

Question 8

What hormone trigger glycogenolysis in the muscles

Answer 8

Adrenaline

Question 9

What is primary function of glucagon

Answer 9

Glucagon increases blood glucose levels by activating processes like glycogenolysis and gluconeogenesis

Question 10

Under what conditions is glucagon secreted

Answer 10

Glucagon is secreted during fasting, low blood glucose, exercise, amino acid presence and stress

Question 11

How does the adrenaline affect fuel mobilisation

Answer 11

Adrenaline primes the body for fight or flight by increasing heart rate, bronchodilation, and blood glucose levels through glycogenolysis and lipolysis

Question 12

What receptor type glucagon and adrenaline bind to in their signalling pathways

Answer 12

GPCRs

Question 13

How do glucagon and adrenaline increase cAMP levels

Answer 13

By activating adenylyl cyclase through the GPCR signalling pathway, which converts ATP to cAMP

Question 14

What does Protein Kinase A PKA do in the glucagon/adrenaline pathway

Answer 14

PKA activates or inhibits downstream enzymes involved in processes like glycogenolysis and lipolysis by phosphorylating target proteins

Question 15

How is glycogenolysis regulated in muscle versus liver tissues

Answer 15

Glucagon regulates glycogenolysis in the liver, while adrenaline regulates it in muscles

Question 16

What enzyme catalyses the conversion of glycogen to glucose-1-phosphate

Answer 16

Glycogen phosphorylase

Question 17

How is glucose-1-phosphate from glycogen breakdown converted for glycolysis in muscles

Answer 17

It is converted to glucose-6-phosphate by the enzyme phosphoglucomutase and used in glycolysis

Question 18

What enzyme metabolises cAMP leading to signal downregulation

Answer 18

Phosphodiesterase PDE

Question 19

How does caffeine affect signal transduction in fuel mobilisation (down regulation)

Answer 19

Caffeine inhibits phosphodiester PDE which prolongs the action of cAMP, thus maintaining the activation of PKA and fuel mobilisation process

Question 20

What is the role of phosphatases in down regulation signalling pathways

Answer 20

Phosphatases remove phosphate groups from phosphorylated protein, resetting the signalling pathways

Question 21

How are FFAs transported after being released from adipose tissues

Answer 21

FFAs are bound to albumin and transported to tissues for energy use via B oxidation

Question 22

What happens to the glycerol released from lipolysis

Answer 22

Glycerol is transported to the liver, where it can be used for gluconeogenesis to synthesise new glucose

Question 23

How does glucagon stimulate B oxidation

Answer 23

Glucagon upregulates gene required for B-oxidation, such as carnitas acyltransferase, down regulated DNL

Question 24

Why is proteins not a primary fuel source

Answer 24

There are no specific storage proteins, and degrading too much protein for energy causes structural and functional damage

Question 25

Main fuels used during aerobic exercise

Answer 25

Glucose and Fatty acids, which undergo oxidative metabolism to produce ATP

Question 26

What fuel source is primarily used for anaerobic exercise

Answer 26

Muscle glycogen, which is converted to glucose-6-phosphate and undergoes glycolysis to produce ATP

Question 27

What is phosphocreatine and what role does it play in energy metabolism

Answer 27

Phosphocreatine is a high-energy phosphate compound that provides a Fast Fuel source by transferring its phosphate to ADP to form ATP during intense exercise - substrate level phosphorylation

Question 28

What is the difference between aerobic and anaerobic ATP productions

Answer 28

Aerobic - ATP production involves CAC and Oxidative phosphorylation
Anaerobic - ATP production is through substrate level phosphorylate in glycolysis without O2.