As we should all know, there are many different kinds of alcohol in this world, some that if we drank them would kill us. But the kind us humans like to drink is the alcohol ethanol (image of molecule above) which is made up of oxygen, hydrogen and carbon. This particular kind of alcohol is a water soluble, which means it enters the blood stream right away and is carried to the liver and the brain, affecting how we feel physically and mentally. But with that it is also a fat soluble, which means it can access of types of cell membranes that are usually off limits.
Why do we get things like impaired vision, and slurred speech? Well that answer is still uncertain, but there are several theories as to why. One that seems to be most consistent is that the ethanol molecule attaches its self to the glutamate receptors, which slows down the the transfers of information from the brain to the other body parts. So instead of getting the chemical signals from other parts of the brain, the glutamate receives the ethanol. Along with this the ethanol receptors also combine with the GABA receptors which are used to slow down brain function. Once these are combined it increases the power of the GABA receptors and slows down brain function even more.
So now even tho I know this, and to all the people who read this, it is interesting to know why we get drunk. Whether it stops us from drinking or not is entirely a different question.