– A section example from our course
Alcohol and Its Effects on the Body
Alcohol is the most widely available drug in the United States, and it is also the most commonly abused. Its impact is particularly felt in terms of traffic crashes.
In 2010 there were 235,461 traffic crashes in Florida, 17,748 of which were related to alcohol use. If you're pretty good at math, then you've already figured out that comes to only about 7.5% of the overall crashes in Florida. So why worry? Well, of 2,444 recorded traffic related fatalities, 794 were related to alcohol use. That means that 32% of the people killed in traffic crashes died because someone chose to drink irresponsibly.1
Among teens the statistics are even worse. A 2008 report from the Department of Transportation showed that car crashes are the leading cause of death among teens, with one out of three fatal teen crashes being alcohol related.2
It might be easy to be skeptical of such a claim. After all, how could just a beer or two really affect your driving? You're just a little "buzzed," right? And "being buzzed" from maybe a beer or two is not the same as "being impaired." Right? Wrong. In the following chapters we will look at how alcohol and other drugs can harm your body and affect your driving, often fatally, in even what we might think are small amounts.
How Alcohol Affects Your Body
Alcohol is a Depressant
Before we can examine how alcohol affects your driving ability, it's important to know how it affects your body. Alcohol is usually consumed by drinking beers, wines, and various types of liquors. It is a part of a class of drugs known as "depressants," which are the opposite of "stimulants." What exactly does that mean? Very simply, depressants slow your central nervous system down, while stimulants speed things up.
Does this sound counter-intuitive? If alcohol slows things in your central nervous system down, then why do people seem more animated and excitable when they drink? As we will see, these characteristics have much less to do with the slowing down of a person's central nervous system, and much more to do with a loosening of inhibitions occurring in the brain.
Taking It All In: How Alcohol Enters and is Absorbed by the Body
When you drink, alcohol is absorbed by the stomach and small intestine. Around 20% of the alcohol is absorbed by stomach and the other 80% is absorbed by your small intestine.3 The exact rate of absorption can vary depending on how concentrated the alcohol is and if you've just eaten a meal.4 In general, the stronger the alcohol (higher concentration) will be absorbed more quickly. In addition, a person that has a relatively empty stomach will feel the effects of alcohol much more quickly than the person who has just eaten a big meal.5
So does that mean that if you just eat a lot of food you'll be fine and won't feel the effects of alcohol? No way. It just means that it will take a bit longer for the full effect of alcohol to creep up on you (and often times it will be much worse when it does!).
Once alcohol is absorbed, it enters your bloodstream and travels throughout your body. You may feel calm and sluggish, but your body is actually working very hard to get rid of the alcohol you consume. This taxes your kidneys and lungs which remove about 10 percent of the alcohol in your urine and breath.6 The rest of the alcohol is broken down by your liver which has to work especially hard to eliminate it from the body. However, until it is eliminated, the alcohol circulates in your bloodstream.
The amount of alcohol in your bloodstream is referred to as your blood alcohol level (BAL). This is measured as weight per unit volume, such as 0.08 (often referred to as simply a ".08 BAL"). This is the same blood alcohol level which is measured by police officers and authorities in determining impaired drivers. We'll return to this later, but it turns out that the concentration of alcohol in a person's breath and urine closely match the concentration in a person's blood. That's why authorities often administer breath and urine tests when they are trying to determine the blood alcohol level of a person.7
A number of factors affect your blood alcohol level, but some of the most significant involve how the alcohol in your body is distributed and absorbed by the tissues in your body.
One of the things that affects the absorption of alcohol in your body is the body weight and build of a person. In general, a larger person will be less affected than a smaller person when consuming the same quantity of alcohol.8 That doesn't mean that the larger person will not be affected by alcohol; it just means that the person will be less affected by alcohol. This is because there is simply more volume in which the alcohol can be distributed both in blood and body tissues.
Think of it this way: if you take a sugar cube and drop it in a glass of water and you take another sugar cube and drop it in a tub of water, which will be sweeter? The water in the glass of course because the sugar has less space to spread out and is more concentrated (on a side note, drinking out of a tub is just gross no matter how sweet the water is!). In the same way, alcohol is more "concentrated" in the body of a smaller person than in the body of a larger person.
Another thing that affects the alcohol absorption is the amount of fat and muscle in a person.9 Alcohol can mix much more easily with water than fat. Muscle tissue has a lot of water in it and can soak up alcohol like a sponge. Fatty tissues on the other hand do not soak up alcohol as readily. That means that if you take two people that weigh the same and one of them has more muscle mass and less fat, he will feel the effects of drinking less than the person who has more fat.
Gender is another important factor that affects the absorption of alcohol in the body.10 In general, females are unable to absorb as much alcohol as males. Think back to the discussion we just had about body mass and how muscle and fat distribution affect the absorption of alcohol. On average, females have less mass and less muscle than males. That means that the alcohol will have less volume in which to be diluted and less muscle to absorb it. Both of these factors mean that females on average will be able to absorb less alcohol than males.
There's also another factor that creates a gender difference in the ability to both absorb and eliminate alcohol. In order to break down alcohol, your body uses a special enzyme located in the stomach and liver called alcohol dehydrogenase (ADH). Females have less of this enzyme than males do, meaning that less alcohol can be broken down. This affects both the absorption and elimination of alcohol.
Rate of Absorption of Alcohol
It takes 20 to 40 minutes after a drink has been consumed for all of the alcohol to be absorbed by the body.11 This is one of the reasons that your blood alcohol level (BAL) will continue to rise for a while even after you stop drinking! Your highest blood alcohol level will often be after you stop drinking.