Ethanol : This molecule, made of little more than a few carbon atoms, is responsible for drunkenness. Often simply referred to as alcohol, ethanol is the active ingredient in alcoholic beverages. Its simplicity helps it sneak across membranes and nestle into a many different nooks, producing a wide range of effects compared to other, clunkier molecules. So how exactly does it cause drunkenness, and why does it have dramatically different effects on different people? To answer these questions, we’ll need to follow alcohol on its journey through the body. Alcohol lands in the stomach and is absorbed into the blood through the digestive tract,especially the small intestine. The contents of the stomach impact alcohol’s ability to get into the blood because after eating, the pyloric sphincter, which separates the stomach from the small intestine, closes. So the level of alcohol that reaches the blood after a big meal might only be a quarter thatfrom the same drink on an empty stomach