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Encyclopedia entry: carbon dioxide
- Article from:
- The Oxford Companion to the Body
- Author:
Copyright© The Oxford Companion to the Body 2001, originally published by Oxford University Press 2001. (Hide copyright information)
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carbon dioxide
When the body ‘burns’ food the end products are mainly water and carbon dioxide, together with some nitrogenous chemicals such as urea. The carbon dioxide enters the bloodstream, is carried to the
lungs
, and is excreted in the expired air of
breathing
. The atmospheric air we inhale contains virtually no carbon dioxide, whereas there is about 5% in the air we breathe out.
Carbon dioxide reacts in the blood to form carbonic acid and bicarbonate and, if it were allowed to accumulate, would cause acidosis. This condition is particularly harmful to the cells of the brain. Carbon dioxide diffuses into the liquid in the brain, the
cerebrospinal fluid
(CSF); any excess ...