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How Alcohol Works

After drinking it, alcohol gets absorbed through the stomach and small intestines and reaches peak blood concentrations anywhere from 30 to 90 minutes after ingestion. Drinking rapidly, drinking on an empty stomach, or drinking beverages with high alcohol concentrations will all shorten the time that it takes to reach peak concentrations. However, if the stomach is inundated by too much alcohol it will secrete mucus and close the pyloric valve, thus slowing the absorption of alcohol into the body.

Alcohol is water soluble and once in the blood system spreads rapidly to all parts of the body. The ways in which alcohol has its effects on the brain remain incompletely understood. Alcohol can dissolve into cell membranes and thus alter the way in which neurons in the brain send signals to one another. It may also stimulate ion channels associated with particular neurotransmitters in the brain.

Alcohol decreases brain activity by increasing the actions of GABA (GABA inhibits the actions of many brain centers) and by decreasing the actions of Glutamate (Glutamate stimulates the actions of many brain centers). This allows one to feel calmer and less inhibited.

Alcohol also stimulates the dopaminergic reward pathway in the brain, which leads to a sense of wellbeing and reward and reinforces the behavior of drinking alcohol.

Alcohol's effects are dependent on the amount of it in one's blood circulation (see here for more information). One drink of alcohol, which is defined as a 12 g of Ethanol, or approximately 12 oz of regular beer, 5 oz of wine or 1.5 oz of 80 proof hard alcohol, will give a blood alcohol content of 0.02%, or 20mg/dl, in a 150 lb man. This is the amount of alcohol that the body can metabolize in one hour. One's blood alcohol content can be estimated based one's weight, gender and number of drinks by using an Alcohol Impairment Chart.

About 90% of the alcohol in one's body will be metabolized by the liver at a rate of about 15mg/dl an hour, though long-term heavy drinkers can metabolize up to three times this amount. Alcohol Dehydrogenase is an enzyme in the liver that converts alcohol to acetaldehyde, a toxic compound that causes nausea and vomiting. The acetaldehyde is then converted by a second liver enzyme, called Aldehyde Dehydrogenase, into acetic acid, an innocuous compound that gets excreted in the urine.

Of the remaining 10% of alcohol in one's body, half is excreted by the kidneys, and half is breathed out through the lungs (which is the basis for the Breathalyzer test).


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Alcohol Overview

Regular Alcohol Use