How Alcohol Works
If you have ever seen a person who has had too much to drink, you know that alcohol is a drug that has widespread effects on the body, and the effects vary from person to person. People who drink might be the "life of the party" or they might become sad and droopy. Their speech may slur and they may have trouble walking. It all depends on the amount of alcohol consumed, a person's history with alcohol and a person's personality.
Even though you have seen the physical and behavioral changes, you might wonder exactly how alcohol works on the body to produce those effects. What is alcohol? How does the body process it? How does the chemistry of alcohol work on the chemistry of the brain? In this article, we will examine all of the ways in which alcohol affects the human body.
What is Alcohol?
In order to understand alcohol's effects on the body, it is helpful to understand the nature of alcohol as a chemical, so let's take a look...
Here are several facts:
Alcohol is a clear liquid at room temperature.
Alcohol is less dense and evaporates at a lower temperature than water (this property allows it to be distilled -- by heating a water and alcohol mixture, the alcohol evaporates first).
Alcohol dissolves easily in water.
Alcohol is flammable (so flammable that it can be used as a fuel).
Alcohol can be made by four different methods:
Fermentation of fruit or grain mixtures
Distillation of fermented fruit or grain mixtures (Spirits such as whiskey, rum, vodka and gin are distilled.)
Chemical modification of fossil fuels such as oil, natural gas or coal (industrial alcohol)
Chemical combination of hydrogen with carbon monoxide (methanol or wood alcohol)
Ethyl Alcohol
The alcohol found in alcoholic beverages is ethyl alcohol (ethanol). The molecular structure of ethanol looks like this:
H
H3 C - C - O - H
H
In this structure, C is carbon, H is hydrogen, O is oxygen and the hyphens are the chemical bonds between the atoms. For purposes of clarity, the bonds between the three hydrogen atoms and the left carbon atom are not shown. The OH (O-H) group on the molecule is what gives it the specific chemical properties of an alcohol. For the remainder of this article, when we say "alcohol," we mean ethanol.
You will not find pure alcohol in most drinks; drinking pure alcohol can be deadly because it only takes a few ounces of pure alcohol to quickly raise the blood alcohol level into the danger zone. For various types of beverages, the ethanol concentration (by volume) is as follows:
Beer = 4 to 6 percent (average of about 4.5 percent)
Wine = 7 to 15 percent (average of about 11 percent)
Champagne = 8 to 14 percent (average of about 12 percent)
Distilled spirits (e.g. rum, gin, vodka, whiskey) = 40 to 95 percent
Most of the typical spirits purchased in liquor stores are 40 percent alcohol.
Some highly concentrated forms of rum and whisky (75 to 90 percent) can be purchased in liquor stores.
Some highly concentrated forms of whiskey (i.e. moonshine) can be made and/or purchased illegally.
How Alcohol Enters the Body
When a person drinks an alcoholic beverage, about 20 percent of the alcohol is absorbed in the stomach and about 80 percent is absorbed in the small intestine. How fast the alcohol is absorbed depends upon several things:
The concentration of alcohol in the beverage - The greater the concentration, the faster the absorption.
The type of drink - Carbonated beverages tend to speed up the absorption of alcohol.
Whether the stomach is full or empty - Food slows down alcohol absorption.
After absorption, the alcohol enters the bloodstream and dissolves in the water of the blood. The blood carries the alcohol throughout the body. The alcohol from the blood then enters and dissolves in the water inside each tissue of the body (except fat tissue, as alcohol cannot dissolve in fat). Once inside the tissues, alcohol exerts its effects on the body. The observed effects depend directly on the blood alcohol concentration (BAC), which is related to the amount of alcohol consumed. The BAC can rise significantly within 20 minutes after having a drink.
How Alcohol Leaves the Body
Once absorbed by the bloodstream, the alcohol leaves the body in three ways:
The kidney eliminates 5 percent of alcohol in the urine.
The lungs exhale 5 percent of alcohol, which can be detected by breathalyzer devices.
The liver chemically breaks down the remaining alcohol into acetic acid.
As a rule of thumb, an average person can eliminate 0.5 oz (15 ml) of alcohol per hour. So, it would take approximately one hour to eliminate the alcohol from a 12 oz (355 ml) can of beer.
The BAC increases when the body absorbs alcohol faster than it can eliminate it. So, because the body can only eliminate about one dose of alcohol per hour, drinking several drinks in an hour will increase your BAC much more than having one drink over a period of an hour or more.
The Effects of Alcohol
If you have seen someone who has had too much to drink, you've probably noticed definite changes in that person's performance and behavior. The body responds to alcohol in stages, which correspond to an increase in BAC:
1. Euphoria (BAC = 0.03 to 0.12 percent)
They become more self-confident or daring.
Their attention span shortens.
They may look flushed.
Their judgement is not as good -- they may say the first thought that comes to mind, rather than an appropriate comment for the given situation.
They have trouble with fine movements, such as writing or signing their name.
2. Excitement (BAC = 0.09 to 0.25 percent)
They become sleepy.
They have trouble understanding or remembering things (even recent events).
They do not react to situations as quickly (if they spill a drink they may just stare at it).
Their body movements are uncoordinated.
They begin to lose their balance easily.
Their vision becomes blurry.
They may have trouble sensing things (hearing, tasting, feeling, etc.).
3. Confusion (BAC = 0.18 to 0.30 percent)
They are confused -- might not know where they are or what they are doing.
They are dizzy and may stagger.
They may be highly emotional -- aggressive, withdrawn or overly affectionate.
They cannot see clearly.
They are sleepy.
They have slurred speech.
They have uncoordinated movements (trouble catching an object thrown to them).
They may not feel pain as readily as a sober person.
4. Stupor (BAC = 0.25 to 0.4 percent)
They can barely move at all.
They cannot respond to stimuli.
They cannot stand or walk.
They may vomit.
They may lapse in and out of consciousness.
5. Coma (BAC = 0.35 to 0.50 percent)
They are unconscious.
Their reflexes are depressed (i.e. their pupils do not respond appropriately to changes in light).
They feel cool (lower-than-normal body temperature).
Their breathing is slower and more shallow.
Their heart rate may slow.
They may die.
6. Death (BAC more than 0.50 percent) - The person usually stops breathing and dies.
If you have ever seen a person who has had too much to drink, you know that alcohol is a drug that has widespread effects on the body, and the effects vary from person to person. People who drink might be the "life of the party" or they might become sad and droopy. Their speech may slur and they may have trouble walking. It all depends on the amount of alcohol consumed, a person's history with alcohol and a person's personality.
Even though you have seen the physical and behavioral changes, you might wonder exactly how alcohol works on the body to produce those effects. What is alcohol? How does the body process it? How does the chemistry of alcohol work on the chemistry of the brain? In this article, we will examine all of the ways in which alcohol affects the human body.
What is Alcohol?
In order to understand alcohol's effects on the body, it is helpful to understand the nature of alcohol as a chemical, so let's take a look...
Here are several facts:
Alcohol is a clear liquid at room temperature.
Alcohol is less dense and evaporates at a lower temperature than water (this property allows it to be distilled -- by heating a water and alcohol mixture, the alcohol evaporates first).
Alcohol dissolves easily in water.
Alcohol is flammable (so flammable that it can be used as a fuel).
Alcohol can be made by four different methods:
Fermentation of fruit or grain mixtures
Distillation of fermented fruit or grain mixtures (Spirits such as whiskey, rum, vodka and gin are distilled.)
Chemical modification of fossil fuels such as oil, natural gas or coal (industrial alcohol)
Chemical combination of hydrogen with carbon monoxide (methanol or wood alcohol)
Ethyl Alcohol
The alcohol found in alcoholic beverages is ethyl alcohol (ethanol). The molecular structure of ethanol looks like this:
H
H3 C - C - O - H
H
In this structure, C is carbon, H is hydrogen, O is oxygen and the hyphens are the chemical bonds between the atoms. For purposes of clarity, the bonds between the three hydrogen atoms and the left carbon atom are not shown. The OH (O-H) group on the molecule is what gives it the specific chemical properties of an alcohol. For the remainder of this article, when we say "alcohol," we mean ethanol.
You will not find pure alcohol in most drinks; drinking pure alcohol can be deadly because it only takes a few ounces of pure alcohol to quickly raise the blood alcohol level into the danger zone. For various types of beverages, the ethanol concentration (by volume) is as follows:
Beer = 4 to 6 percent (average of about 4.5 percent)
Wine = 7 to 15 percent (average of about 11 percent)
Champagne = 8 to 14 percent (average of about 12 percent)
Distilled spirits (e.g. rum, gin, vodka, whiskey) = 40 to 95 percent
Most of the typical spirits purchased in liquor stores are 40 percent alcohol.
Some highly concentrated forms of rum and whisky (75 to 90 percent) can be purchased in liquor stores.
Some highly concentrated forms of whiskey (i.e. moonshine) can be made and/or purchased illegally.
How Alcohol Enters the Body
When a person drinks an alcoholic beverage, about 20 percent of the alcohol is absorbed in the stomach and about 80 percent is absorbed in the small intestine. How fast the alcohol is absorbed depends upon several things:
The concentration of alcohol in the beverage - The greater the concentration, the faster the absorption.
The type of drink - Carbonated beverages tend to speed up the absorption of alcohol.
Whether the stomach is full or empty - Food slows down alcohol absorption.
After absorption, the alcohol enters the bloodstream and dissolves in the water of the blood. The blood carries the alcohol throughout the body. The alcohol from the blood then enters and dissolves in the water inside each tissue of the body (except fat tissue, as alcohol cannot dissolve in fat). Once inside the tissues, alcohol exerts its effects on the body. The observed effects depend directly on the blood alcohol concentration (BAC), which is related to the amount of alcohol consumed. The BAC can rise significantly within 20 minutes after having a drink.
How Alcohol Leaves the Body
Once absorbed by the bloodstream, the alcohol leaves the body in three ways:
The kidney eliminates 5 percent of alcohol in the urine.
The lungs exhale 5 percent of alcohol, which can be detected by breathalyzer devices.
The liver chemically breaks down the remaining alcohol into acetic acid.
As a rule of thumb, an average person can eliminate 0.5 oz (15 ml) of alcohol per hour. So, it would take approximately one hour to eliminate the alcohol from a 12 oz (355 ml) can of beer.
The BAC increases when the body absorbs alcohol faster than it can eliminate it. So, because the body can only eliminate about one dose of alcohol per hour, drinking several drinks in an hour will increase your BAC much more than having one drink over a period of an hour or more.
The Effects of Alcohol
If you have seen someone who has had too much to drink, you've probably noticed definite changes in that person's performance and behavior. The body responds to alcohol in stages, which correspond to an increase in BAC:
1. Euphoria (BAC = 0.03 to 0.12 percent)
They become more self-confident or daring.
Their attention span shortens.
They may look flushed.
Their judgement is not as good -- they may say the first thought that comes to mind, rather than an appropriate comment for the given situation.
They have trouble with fine movements, such as writing or signing their name.
2. Excitement (BAC = 0.09 to 0.25 percent)
They become sleepy.
They have trouble understanding or remembering things (even recent events).
They do not react to situations as quickly (if they spill a drink they may just stare at it).
Their body movements are uncoordinated.
They begin to lose their balance easily.
Their vision becomes blurry.
They may have trouble sensing things (hearing, tasting, feeling, etc.).
3. Confusion (BAC = 0.18 to 0.30 percent)
They are confused -- might not know where they are or what they are doing.
They are dizzy and may stagger.
They may be highly emotional -- aggressive, withdrawn or overly affectionate.
They cannot see clearly.
They are sleepy.
They have slurred speech.
They have uncoordinated movements (trouble catching an object thrown to them).
They may not feel pain as readily as a sober person.
4. Stupor (BAC = 0.25 to 0.4 percent)
They can barely move at all.
They cannot respond to stimuli.
They cannot stand or walk.
They may vomit.
They may lapse in and out of consciousness.
5. Coma (BAC = 0.35 to 0.50 percent)
They are unconscious.
Their reflexes are depressed (i.e. their pupils do not respond appropriately to changes in light).
They feel cool (lower-than-normal body temperature).
Their breathing is slower and more shallow.
Their heart rate may slow.
They may die.
6. Death (BAC more than 0.50 percent) - The person usually stops breathing and dies.
