Integration + Regulation Of Metabolism Flashcards
Describe the metabolism specialisation of brain?
Uses 100-200g glucose daily
Over 1/2 energy consumed is used for Na+—K+ transport to maintain membrane potential and synthesis of neurotransmitters
Lacks energy stores
Glucose is transported by GLUT3 which has a low Km so is saturated under most conditions
Normally fatty acids are used not for energy but for membrane biosynthesis
Describe the metabolic specialisation of cardiac muscle?
Is exclusively aerobic with little/no glycogen stores
Fatty acids are main source of energy followed by lactate + ketone bodies
Describe the metabolic specialisation of adipose tissue?
Reservoir metabolic energy in form of triglycerides
Although liver makes fatty acids, we get most from our diet
These are delivered by chylomicrons
Glucose is transported by GLUT4 which is insulin sensitive
What is metabolic specialisation of kidney?
Major role is to produce urine
Plasma is filtered up to 60 times daily
Only small volume of urine is produced
Water soluble material is largely reabsorbed to prevent loss
During starvation, kidney may contribute 1/2 of blood glucose through gluconeogensis
Describe the metabolic specialisation of liver?
Play a central role in regulating metabolism
Most compound absorbed by gut pass through liver
Provides fuel for brain, muscle + other peripheral organs
Takes its energy from a-ketoacids
What enzymes are involved in control of blood glucose by liver metabolism?
Glucose is transported into hepatocytes by GLUT2 + immediately phosphorylated by glucokinase to form G6P
G6P from glycogen breakdown or gluconeogensis is converted to glucose by glucose 6 phosphatase + transported out of cell + into blood by GLUT2
What enzyme is involved in muscle glucose metabolism?
Glucose is converted to G6P by hexokinase
Compare hexokinase and glucokinase
Glucokinase is present ONLY in liver and has a HIGH Km
Hexokinase is present in ALL tissues of body including liver and has a LOW Km
