Integration Of Whole Body Metabolism Flashcards
How much glucose does the brain use daily?
100-120g
What is over half the energy consumed used for in the brain?
Sodium potassium transport to maintain membrane potential and in synthesis of neurotransmitters
What is glucose B transported by?
GLUT3
What is the danger point for plasma glucose levels in the brain?
Below 2.2mM
What are fatty acids used for normally in the brain?
Membrane biosynthesis
How does the cardiac muscle respire?
Aerobically
Does cardiac muscle have glycogen stores?
No (possibly a tiny bit?)
What is the main source of energy for cardiac muscle?
Fatty acids
What sources of energy can cardiac muscle use (not fatty acids)?
Lactate and ketone bodies
What is adipose tissues function?
Reservoir of metabolic energy in the form triglycerides
How much TG will a 70kg man store?
15kg
Where do TGs come from?
Diet or chylomicron
Where are TGs synthesised?
Liver
What are TGs transported by after synthesis?
VLDLs
What is glucose transported by?
GLUT4
What is GLUT 4 sensitive to?
Insulin
How many times daily is plasma filtered in the kidney?
Up to 60 times
Why is water soluble material largely reabsorbed in the kidney?
To prevent loss
How much energy do the kidneys consume?
10%
How much blood glucose does the kidney contribute during starvation?
Half
What molecules does the liver metabolise?
Carbs
Fatty acids
Amino acids
What does the liver provide fuel for?
Brain, muscle and other peripheral organs
What happens in the liver after glucose is transported in hepatocytes by glut2?
Immediately phosphorylated by glucokinase
Where does G6P come from in the liver?
Glycogen breakdown or gluconeogenesis
What enzyme is used to take G6P-glucose?
G6Phosphatase
How is glucose transported out of the hepatocyte cell?
GLUT2
What happens if the blood glucose gets about 6.6mm?
Glucose enters the hepatocytes by the GLUT 2 transport molecule
What is the glucokinases km level?
Low
What does it mean if molecules have a low km?
Saturated at high levels of glucose
What enzyme facilitates the glucose-> G6P reaction?
Hexokinase
What is the km for glucose?
0.1mM
What is the concentration of glucose inside cells?
Low
What does an increase in insulin lead to in muscle cells?
Increase in glucose uptake by glut4
Do muscle cells use hexokinase or glucokinase?
Hexokinase
When sprinting, what is power and speed dependant on?
Availability of ATP
What is creatine phosphate?
Relatively small but rapidly mobilised ATP store which only lasts a few seconds
Creatine phosphate + ADP->?
ATP + creatinine enzyme
What is the creatinine enzyme called?
Creatinine kinase
What does build up of lactase cause?
Fall in pH
How do cells respire in a marathon?
Aerobic respiration
What does aerobic respiration for a marathon require the cooperation of?
Muscle, liver and adipose tissue
How much slower is metabolism with fats as compared to creatine
10x slower
When the body is fed, what process increase?
Glycolysis
Glycogen synthesis
Fatty acid synthesis
When the body is fed, what molecules increase?
Glycogen
Fatty acids
When the body is fed, what process decrease?
Glycogenolysis
Gluconeogenolysis
Fatty acid degredation
When the body is fed, what molecules decrease?
Glucose
Ketone bodies
What is the first priority for the body when starved?
Maintain glucose levels
What is the second priority for the body when starved?
Preserve proteins
How does the body preserve proteins in starvation?
Metabolism shifts from glucose to fatty acids and ketone bodies
When is the post absorptive phase?
Several hours after the last meal
What happens in the post absorptive phase?
- blood glucose falls, insulin levels fall and glucose levels rise
- phosphorylase a activity increase as does glycogen breakdown
- drop in insulin reduces glucose uptake by muscle and adipose tissues
When the body is starved, what process decrease?
Glycolysis
Glycogen synthesis
Fatty acid synthesis
When the body is starved, what molecules decrease?
Glycogen
Fatty acids
When the body is starved, what process increase?
Glyconeogenesis
Gluconeogenesis
Fatty acid degredation
When the body is starved, what molecules increase?
Glucose
Ketone bodies
When is early starvation?
24hrs
What happens in early starvation
- Glucose released from liver due to gluconeogenesis and glycogenolysis
- mobilisation of FAs from adipose tissue
- glucose use falls as muscle switches to FA oxidation
- initial increase in protein breakdown
What happens to the energy after 12 hrs of starvation?
45% of resting energy from FA and 40% from glucose
When is intermediate starvation?
3-20 days
What happens in intermediate starvation?
- glycogen stores depleted
- increased lipolysis and ketogenesis
- increased gluconeogenesis to maintain blood glucose
- further starvation means the kidney takes over gluconeogenesis from the liver
What happens to the beta hydroxybutyrate after 8 days?
Raised 50fold
How long is prolonged starvation?
More than three weeks
What happens in prolonged starvation?
- Other sources of gluconeogenic precursors are lactate and glycerol
- lactate is recycles by the coricycle
- glycerol and amino acids are oxidised
- proteins are broken down by the muscle forming amino acid precursors
When does the betahydroxybutyrate plateau in starvation?
At 20 days
During prolonged starvation, what does the need for glucose fall to?
100g-> 40g/day
