Anion gap: is a
measurement of the anions in the arterial blood (besides
chloride and bicarbonate anions). Arterial blood is blood in the
arteries. Arteries are blood vessels that carry blood away from
the heart. Chloride is a combination of the element, chlorine,
with another element. Bicarbonate is a substance in the blood
that prevents it from becoming too acidic or too alkaline
(non-acidic).