Once alcohol is ingested, some of the ethanol is metabolized in the stomach by an enzyme called alcohol dehydrogenase. However, the stomach is not the primary site for alcohol metabolism. Any un-metabolized alcohol is absorbed into the bloodstream through the stomach and small intestine. The blood is transported to the liver, where the majority of alcohol metabolism occurs. Therefore, any alcohol that is un-metabolized enters the systemic circulation and travels throughout the body until the liver can metabolize it.
Alcohol is water soluble and therefore is absorbed primarily by water in the body.
Absorption sites include the blood and the water fluid inside and surrounding the cells. The alcohol is therefore absorbed by most organs including the brain. With an ethanol molecule present, this enzyme binds more tightly to its substrate. Extremely high or low levels of these ions can cause respiratory problems as well as heart beat irregularities. Death occurs most often when a person drinks in excess and passes out.