Alcohol & the Human Body

When it comes to fighting a DWI, it’s helpful to know how alcohol affects the human body. Although everyone metabolizes alcohol differently, depending on weight, gender, metabolic rate, and other factors, the central processes are the same for everyone. With knowledge of how alcohol metabolizes in the body, a New York drunk driving defense lawyer can analyze the factors in a specific case to challenge chemical tests and craft a successful defense.

Alcohol is a central nervous system depressant. The degree to which the central nervous system function is impaired is directly proportional to the concentration of alcohol in the blood. There are three stages of alcohol metabolism: Absorption, distribution, and elimination.

Absorption is the process wherein alcohol enters the body, and then the bloodstream, where it can be distributed throughout the body. Unlike most other ingested substances, alcohol is not digested, and can be absorbed unchanged directly through the stomach lining. Because of its large surface area, the small intestine absorbs much more alcohol than the stomach, which has a far smaller surface area.

As alcohol is absorbed, blood alcohol content (BAC) increases until it reaches a peak concentration, then gradually tapers off. It generally takes 30 to 60 minutes to reach peak alcohol levels after a person stops drinking.

Once alcohol is absorbed by the gastrointestinal tract, it enters the bloodstream and is rapidly distributed throughout all of the water-containing components of the body. Because it is distributed so quickly and thoroughly, alcohol can affect the central nervous system even in small concentrations.

The bloodstream transports the alcohol to the bodily tissues. Veins carry the blood to and through the lungs where the blood becomes oxygenated. Arteries then carry the oxygen-rich blood to the brain and the rest of the body. Because alcohol it completely soluble in water, the alcohol content in the whole body is directly proportional to total body water content. Water content varies from person to person.

In general, the less a person weighs, the more he or she will be affected by a given amount of alcohol. This is because there is less water in a smaller person than in a larger person. For people of the same weight, a well-muscled individual will be less affected than someone with a higher percentage of fat, since fatty tissue does not contain very much water and will not absorb very much alcohol.

Women are more affected by alcohol consumption than men, because in general women have more fat and less water in their bodies. About 68 percent of a man’s body weight is water, while only about 55 percent of a woman’s body is water weight.

Approximately 15 to 45 minutes after a person consumes his or her last drink, the body begins to eliminate alcohol through metabolism, excretion, and evaporation. Metabolism accounts for approximately 95 percent of alcohol elimination. The liver is responsible for metabolism. As a rule of thumb, a person metabolizes one average drink, or five ounces of alcohol, per hour.

Besides gender, body weight, and other factors affecting metabolic rates, there are several additional factors to consider when it comes to alcohol metabolism. Healthy people process alcohol more efficiently than unhealthy people. Chronic alcoholics whose livers function properly metabolize alcohol more quickly than the average person. Younger people metabolize alcohol more efficiently than older people.

A small amount of alcohol is eliminated from the body through excretion and evaporation. Alcohol is excreted unchanged through urine, tears, sweat, semen, and saliva. Excretion may account for a person smelling of alcohol. Alcohol evaporates from the blood into the lungs and is excreted in breath, allowing it to be measured in a breath sample. Alcohol elimination rates are inversely proportional to alcohol concentration in the blood. This means that the higher the blood alcohol levels, the slower the rate of elimination.

Even though alcohol is excreted in the breath, not all evaporated air from the lungs is equal in alcohol concentration. The highest alcohol concentration in the lungs comes from the end of a long exhalation of breath, where the air was in closest proximity to the blood. Because of this factor, police ask drivers to blow long and hard during breath testing, because the deep lung air will have the highest concentrations of alcohol and result in a higher BAC.

Eating before drinking alcohol, or consuming food and alcohol together, also will affect the amount of alcohol in the bloodstream. The more food a person has in his or her stomach while drinking, the lower the BAC. This is because having food in the stomach affects the absorption of alcohol by the small intestine. A valve at the bottom of the stomach closes when there is food in the stomach to digest, and prevents alcohol from reaching the small intestine. The alcohol in the stomach is absorbed at a slower rate, which affects the distribution into the bloodstream, and ultimately the rate of elimination.

Police and prosecutors don’t always take these issues into consideration when considering a charge of drunk driving, but many factors affect the metabolism of alcohol. This is of key importance in a drinking and driving case, because chemical tests typically take place an hour or more after police stop a driver, and the person’s BAC at the time of driving must be estimated. A qualified New York attorney with experience defending DWI cases can use these factors to a driver’s advantage, and successfully fight a drunk driving case.