====== Oxidative phosphorylation ======

[[Mitochondria]] are often referred to as the "powerhouses" of the cell because they play a critical role in generating [[energy]] in the form of [[adenosine triphosphate]] (ATP) through a process called [[oxidative phosphorylation]].
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The cerebral metabolic rate of oxygen consumption ([[CMRO2]]) arises from neurons utilizing energy for two functions: 

1) maintenance of cell integrity ([[homeostasis]]) which normally accounts for ≈ 40% of energy consumption, and 2) conduction of electrical impulses. The occlusion of an artery produces a central core of ischemic tissue where the CMRO2 is not met. The oxygen deficiency precludes aerobic [[glycolysis]] and oxidative phosphorylation. [[ATP]] production declines and cell homeostasis cannot be maintained, and within minutes irreversible cell death occurs; a so-called [[cerebral infarction]]. Surrounding this central core is the [[penumbra]], where collateral flow (usually through [[leptomeningeal vessels]]) provides marginal oxygenation which may impair cellular function without immediate irreversible damage. Cells in the penumbra may remain viable for hours.