Glucose storage Flashcards
What tissues have an absolute requirement for glucose as an energy source?
RBC
Neutrophils
Innermost cells of kidney medulla
Lens of the eye
How is glycogen stored?
Granules
What is the difference between liver and muscle stores of glycogen?
Muscle-for muscles use only
Liver stores- used to maintain blood glucose levels
What enzyme is responsible for regulation liver glycogen synthesis?
Glycogen synthase
What enzyme is responsible for regulating liver glycogen degradation?
Glycogen phosphorylase
What effect does glucagon and adrenaline have on glycogen synthase and by what mechanism do they have this effect?
They decrease its activity by phosphorylating it
What effect does glucagon and adrenaline have on glycogen phosphorylase and by what mechanism do they have this effect?
Increase it (want there to be glycogen degradation) by phosphorylating it
What effect does insulin have on glycogen synthase and by what mechanism does it have this effect?
Increases its activity by de-phosphorylating it
What effect does insulin have on glycogen phosphorylase and by what mechanism does it have this effect?
It decreases its activity by de-phosphorylating it
Glucagon has no effect on what tissues?
Muscle’s and their glycogen stores
Give two examples of glycogen storage diseases
Von Gierke’s disease- glucose 6- phosphatase deficiency- hepatomegaly due to not being able to release glycogen as glucose because they’re lacking the right enzyme
McArdle disease- muscle glycogen phosphorylase deficiency- quick exhaustion because they cant mobilise their glycogen stores from their skeletal muscle
What are the 3 main precursors for gluconeogensis?
Lactate-from anaerobic glycolysis in exercising muscle and red blood cells (cori cycle)
Glycerol-released from adipose tissues in the breakdown of triglycerides
Amino acids- mainly Alanine
What are the two main enzymes involved in the regulation of gluconeogenesis?
Fructose 1-6 bisphosphatatse
PEPCK
What effect do glucagon and cortisol have on PEPCK and on gluconeogenesis?
Increase amount of PEPCK and stimulate gluconeogenesis
What effect do glucagon and cortisol have on fructose 1-6 bisphosphatase and on gluconeogenesis?
Increase amount and activity and stimulate gluconeogenesis
