Under normal circumstances, the mammalian CNS is dependent on glucose
supplied from the blood, along with oxygen also supplied from the blood, for
aerobic metabolism. There is very little glycogen in the brain, as well as
very little capability to metabolize other substrates. Therefore,
interruption of the blood flow causes severe impairment of brain function
within seconds. I believe that oxygen is more critical -- one source
(Guyton's Medical Physiology) indicates that carbohydrate stores in the
brain (glycogen) can last a couple of minutes.
The brain has a rich blood supply with special transport mechanisms in the
blood-brain barrier to transport glucose rapidly from the capillaries to the
extra-cellular fluid. The uptake of glucose by neurons is not insulin
dependent, another adaptation for rapid and constant glucose utilization.
Rowland Jenkins wrote in message <7vfbl8$coj$1 at nnrp02.primenet.com>...
>I need the following clarified if possible
>>1. What does a nerve cell's metabolism run on (glucose, oxygen, etc).
>2. How are those nutrients obtained from the blood stream?
>3. Is there a reserve of those nutrients in the nerve cell that has
>to be replenished or is there a continuous transfer from the bloodstream?
>>Thank you in advance for any help.
>>- Rowland
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