Blood Flow
The penumbra region typically occurs when blood flow drops below 20 mL/100 g/min. At this point electrical communication between neurons fails to exist.Cells in this region are alive but metabolic pumps are inhibited, oxidative metabolism is reduced but neurons may begin to depolarize again. Areas of the brain generally do not become infarcted until blood flow to the region drops below 10 to 12 mL/100 g/min. At this point, glutamate release becomes unregulated, ion pumps are inhibited and adenosine triphosphate (ATP) synthesis also stops which ultimately leads to the disruption of intracellular processes and neuronal death.
Read more about this topic: Penumbra (medicine)
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