Lecture 34 Flashcards
What happens to fuel levels in the blood during starvation?
Ketone production increases, FFAs increase to allow glucose to remain relatively constant and protein is utilised initially, then conserved through the total urinary nitrogen
What can the brain utilise as an alternative form of energy to glucose to preserve glucose levels?
Ketone bodies
How are glucose levels maintained without dietary glucose?
New glucose is made in the liver from gluconeogenic precursors (gluconeogenesis)
What are the gluconeogenic precursors?
Glycerol from fat and pyruvate from alanine (muscle)
How are FAs increased during starvation?
Mobilised from adipose to become the prominent fuel for many tissues
How is the production of ketone bodies increased?
Influx of FFAs into the liver and subsequent beta-oxidation that increases acetyl-CoA which drives ketogenesis through catabolism of fat
What do ketone bodies provide?
Acetyl-CoA for CAC and ATP generation in the brain and muscle
What are the metabolic adaptions driven by?
Glucagon in response to low glucose and potentiated by cortisol and adrenaline
What happens to protein in starvation metabolim?
They are spared in the muscle
What is the process of glucagon activating fat mobilisation in the adipose tissue?
Glucagon binds to glucagon receptor which activates G-protein. Adenylyl cyclase is activated from G-protein and uses ATP to send cAMP to protein kinase A to phosphorylate hormone-sensitive lipase to hydrolyse fat
What is the process of glucagon activating gluconeogenesis in the liver?
Glucagon binds to receptor which causes signalling cascade leading to FOX01 activating glucogenic genes
What is gluconeogenesis?
Synthesis of new glucose from lactate from RBCs and muscle, alanine from muscle and glycerol from adipose
Where does gluconeogenesis occur?
Mainly in the liver and some in the kidney
What is gluconeogenesis stimulated by?
Glucagon
What provides the energy and reducing power for gluconeogenesis?
Fatty acid oxidation
