In carbon dioxide in your red blood cells, which causes in ph, causes your breathing to speed up. see concept 42.6 (page 944)

 Increase in carbon dioxide in your red blood cells which causes a drop in PH causes your breathing to speed up. If you hold your breath, rising carbon dioxide blood gas changes first leading to the urge to breathe. Carbon dioxide enters blood at the abdominal organs, hindlimbs, capillaries of the head.

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