In hypoventilation (insufficient ventilation - shallow and/or slow breathing) the lungs gain carbon dioxide in body fluids
(hypercapnia) since the lungs fail to remove carbon dioxide as rapidly as it is being formed. The increased formation of
carbonic acid results in a net gain of hydrogen ions, lowering pH in body fluids. The chemoreceptor feedback causes
ventilation to increase until carbon dioxide levels and extracellular fluid pH return to normal.