There are actually many kinds of alcohol in the chemical world, but the one we drink the most is ethanol. It’s the particular shape of an ethanol molecule that gives a glass of beer or a shot of the hard stuff its specific effects on the human brain. The molecule is very tiny, made up of just two carbon atoms, six hydrogen atoms, and one oxygen atom. Ethanol is water soluble, which means it enters the blood stream readily, there to be carried quickly to all parts of the body (most notably the liver and the brain). It’s also fat soluble; like an all-access pass through various cell membranes and other places that are normally off limits.
A certain portion of the ethanol you drink passes through your stomach to your small intestine, is absorbed into your bloodstream and carried to your brain. That’s what we’re really concerned with. Research has not conclusively determined exactly how ethanol accomplishes all of its various effects in the brain, but there are some well-supported theories. The slow reactions, slurred speech and memory loss of a drunk are probably caused by ethanol attaching to glutamate receptors in your brain’s neural circuitry. These receptors normally receive chemical signals from other parts of the brain, but instead they get an ethanol molecule. This disrupts the flow of signals and generally slows the whole brain down.
Ethanol also binds to GABA (gamma-aminobutyric acid) receptors, which normally serve to slow down brain activity. Unlike glutamate receptors, ethanol actually makes GABA receptors more receptive, causing the brain to slow down even more. But alcohol isn’t simply a depressant, because it also stimulates the production of dopamine and endorphins, chemicals that produce feelings of pleasure. Research hasn’t yet revealed the exact mechanism involved, but it may be similar to the way ethanol stimulates the GABA receptors.
The particular shape of an ethanol molecule makes it ideally suited to getting humans drunk. Slight differences in the charge at each end of the molecule make it both water and fat soluble.
Red atom = Oxygen
White atoms = Hydrogen
Black atoms = Carbon