Lecture 33 - Fuel mobilisation Flashcards
What is fuel mobilisation
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
Carbohydrates - fuel mobilisation
For carbohydrates, the process of glycogenolysis is activated to obtain glucose for glycolysis
Fats - Fuel mobilisation
Lipolysis is activated to obtain FAs for B-oxidation
Proteins - fuel mobilisation
Proteolysis to obtain amino acids for energy
What is glycogenolysis
Glycogenolysis is the process of breaking down of glycogen into glucose, which can be used for glycolysis to produce energy
What is lipolysis
Lipolysis is the breakdown of TAGs in adipose tissue to release free fatty acids and glycerol production through B oxidation
How hormone trigger glycogenolysis in liver
Glucagon
What hormone trigger glycogenolysis in the muscles
Adrenaline
What is primary function of glucagon
Glucagon increases blood glucose levels by activating processes like glycogenolysis and gluconeogenesis
Under what conditions is glucagon secreted
Glucagon is secreted during fasting, low blood glucose, exercise, amino acid presence and stress
How does the adrenaline affect fuel mobilisation
Adrenaline primes the body for fight or flight by increasing heart rate, bronchodilation, and blood glucose levels through glycogenolysis and lipolysis
What receptor type glucagon and adrenaline bind to in their signalling pathways
GPCRs
How do glucagon and adrenaline increase cAMP levels
By activating adenylyl cyclase through the GPCR signalling pathway, which converts ATP to cAMP
What does Protein Kinase A PKA do in the glucagon/adrenaline pathway
PKA activates or inhibits downstream enzymes involved in processes like glycogenolysis and lipolysis by phosphorylating target proteins
How is glycogenolysis regulated in muscle versus liver tissues
Glucagon regulates glycogenolysis in the liver, while adrenaline regulates it in muscles
What enzyme catalyses the conversion of glycogen to glucose-1-phosphate
Glycogen phosphorylase
How is glucose-1-phosphate from glycogen breakdown converted for glycolysis in muscles
It is converted to glucose-6-phosphate by the enzyme phosphoglucomutase and used in glycolysis
What enzyme metabolises cAMP leading to signal downregulation
Phosphodiesterase PDE
How does caffeine affect signal transduction in fuel mobilisation (down regulation)
Caffeine inhibits phosphodiester PDE which prolongs the action of cAMP, thus maintaining the activation of PKA and fuel mobilisation process
What is the role of phosphatases in down regulation signalling pathways
Phosphatases remove phosphate groups from phosphorylated protein, resetting the signalling pathways
How are FFAs transported after being released from adipose tissues
FFAs are bound to albumin and transported to tissues for energy use via B oxidation
What happens to the glycerol released from lipolysis
Glycerol is transported to the liver, where it can be used for gluconeogenesis to synthesise new glucose
How does glucagon stimulate B oxidation
Glucagon upregulates gene required for B-oxidation, such as carnitas acyltransferase, down regulated DNL
Why is proteins not a primary fuel source
There are no specific storage proteins, and degrading too much protein for energy causes structural and functional damage
Main fuels used during aerobic exercise
Glucose and Fatty acids, which undergo oxidative metabolism to produce ATP
What fuel source is primarily used for anaerobic exercise
Muscle glycogen, which is converted to glucose-6-phosphate and undergoes glycolysis to produce ATP
What is phosphocreatine and what role does it play in energy metabolism
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
What is the difference between aerobic and anaerobic ATP productions
Aerobic - ATP production involves CAC and Oxidative phosphorylation
Anaerobic - ATP production is through substrate level phosphorylate in glycolysis without O2.
