Central Nervous System
The following is true about brain metabolism except
|A||Use fatty acid in starvation|
|B||In resting state 60% of total energy utilised|
|C||Option A, B is right|
|D||Has no energy store.|
- Brain metabolism:
- Major substrates for brain are
a. Glucose, Amino acid, and ketone bodies (in starvation)
b. Polyunsaturated fatty acids in neonate
- Brain has no stored energy
- Brain tissue normally use glucose as an exclusive fuel except during starvation when it can adapt to use ketone bodies.
- Under resting condition, the metabolism of the brain accounts for about 15% of the total metabolism in the body.
Therefore, under resting condition, brain metabolism is about 7.5 times the average metabolism in the rest of the body. It means that the brain uses 15% of total energy at resting condition.
- O2 consumption by the human brain (=cerebral metabolic rate for O2, CMRO2) is average 3.5 ml/100gm/of brain/min or 49ml/min for whole brain. Or 20% of the total body resting O2 consumption
VII.Glucose enters the brain via GLUT-l in cerebral capillaries. It is independent of insulin.