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Why is a steady supply of oxygen in the blood especially important for the brain?

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Blood plasma — blood Blood sediment in test tubes, showing plasma (clear fluid), red blood cells (red), and the release of hemoglobin into the surrounding plasma (pink).

A steady supply of oxygen in the blood is critical for the brain because the central nervous system maintains a high metabolic rate and possesses only a very limited store of oxygen and high-energy phosphates.12

Cells, including neurons, rely on aerobic metabolism within their mitochondria to produce adenosine triphosphate (ATP), the energy currency required to fuel essential cellular processes. Because the brain cannot import ATP and has minimal internal reserves, it is exceptionally sensitive to interruptions in circulation. If the oxygen supply is disrupted, even for a few minutes, it leads to unconsciousness and can cause irreversible damage to neurons, resulting in an infarct (an area of dead tissue). Consequently, the brain depends on a continuous, liberal blood supply to meet its constant metabolic demands and to clear metabolic waste products.123