Archived Pages from 20th Century!!
Alcohol and the
Physiology of the Human Body Alcohol is a drug and must be handled
with care. Knowing its uses and abuses is just as important as reading
the instructions on a bottle of pills. It is basic preventive medicine
to know how your body handles alcohol, how much is safe to drink and, finally,
how your body gets rid of it.
When you have a drink, a small amount of alcohol enters the bloodstream directly through the tissues of the mouth and throat. When it reaches the stomach 30 - 40 percent of the alcohol can be absorbed in 20 minutes if the outlet valve of the stomach is closed. When the outlet is open, however, the alcohol passes into the small intestine, where rapid absorption takes place. The bloodstream then distributes the alcohol uniformly throughout the body. In this manner, the alcohol reaches the brain.
Alcohol is an anesthetic. Its effects are similar to ether or chloroform. As a central nervous system depressant, it affects all parts of your body controlled by the brain. Your ability to make appropriate judgments and to exercise self-control is affected. This means that you cannot control the effects of alcohol by an act of will.
Alcohol does not simply pass through you. Like most things we eat or drink, it must be broken down and eliminated. Moreover, alcohol affects the body fairly rapidly, although its impact can be decreased according to a number of factors.
Disposing of alcohol is much more time consuming than drinking. Most alcohol is eliminated by a process called oxidation, which breaks it down into carbon dioxide and water. More than 90 percent of the alcohol is oxidized in the liver and the remainder is discharged unchanged through the lungs and kidneys. Only a negligible proportion is eliminated through tears, saliva and perspiration. You cannot dance, jog, sing, or cry away alcohol. Frequent urination does not help. Nor is the rate of elimination affected by a person's weight or tolerance to alcohol. It takes as long for the experienced drinker to eliminate alcohol as it does for the inexperienced drinker.
Breath - Blood Alcohol Ratio
When alcohol leaves the blood stream and enters the breath it reaches
a point of equilibrium in the "deep lung" or alveolar region. The relationship
between the concentration of alcohol in the arterial blood region of the
lungs and the concentration of alcohol in the breath from the deep lung
region (alveoli) at the end expiratory breath temperature (34 C) is known
as the breath-blood ratio. This ratio has been experimentally determined
by a number of research groups since Widmarks's historic work in this field
and at present the most commonly accepted ratio is 2100:1. That is, 2100
parts of deep lung air contain the same amount of alcohol as 1 part of
Others have found the factor of 2320-2370 to 1 can be established using re-breathed air as a means of breath alcohol determination and have therefore proposed the adoption of 2300:1 as the international standard. While this more closely approximates the value to be predicted from Henry's Law, it does not take into consideration the practical limits of the design of breath testing instruments commonly being used for evidential and screening purposes. Thus, while the ratio of 2100:1 generally results in an under-estimation of blood alcohol concentration from a breath alcohol analysis, this is preferred to an over-estimation when the results of the analysis are to be used to establish a criminal charge or other sanction.
To ensure that a proper sample of breath from the deep lung region has been analyzed for alcohol content, a variety of techniques have been adopted which require a controlled and uninterrupted flow of breath until near complete expiration has occurred. It is the breath from the deep lung region (end expiratory) that contains the highest concentration of alcohol which is in equilibrium with the alcohol concentration of the blood.
Mixed expired breath has a lower alcohol concentration since it is not in equilibrium with the blood. Thus, the means to sample breath for alcohol analysis must ensure that all of the mixed expired air is exhaled first before a sample of breath from the deep lung region is captured for analysis.
Further, to ensure that the alcohol in the breath sample is representative of the alcohol concentration of the blood, one must ensure that there is no concentration of the breath sample from residual alcohol in the mouth and throat from a recent drink. This is accomplished by waiting fifteen (15) minutes after a last drink or rinsing the mouth and swallowing water before conducting a breath test.
Behavior as a Result
of Alcohol Consumption Alcohol affects everyone. It does so, however,
in different ways, depending on your mood, physical condition, personality
and the company you keep. If you are just recovering from a cold or have
had little sleep, the effects of alcohol will be magnified. If you are
worried about your job or your love life, drinking will only compound your
feelings of anxiety and possibly lead to aggressive or hostile behavior.
Your reaction to alcohol will also vary according to the social demands
placed upon you. A few drinks with your friend will make you feel drunker
than a few drinks with the family.
You may learn to compensate for some of the more obvious symptoms of drinking. Researchers call this behavioral tolerance and everyone calls it "holding your liquor". While experienced drinkers can learn the act normally when talking or walking, they cannot control the effects of alcohol on skills demanding fine motor coordination or precise judgment.
Some drinkers develop physical tolerance to alcohol. As a result of prolonged regular drinking, the liver becomes more efficient in breaking down alcohol. In addition, some cells in the brain can become less sensitive to the effects of alcohol. As a result of both of these factors, progressively more alcohol may be needed to produce the mode-altering effects experienced in earlier stages of drinking.
Whatever the individual variations, there is an established sequence of symptoms which correspond to different degrees of intoxication. The first mental processes to be affected are those connected with training or previous experience. One skill impaired at the initial stages of intoxication is driving ability, particularly for individuals who have not been driving very long.
After a few more drinks, the ability to perform familiar and habitual tasks requiring relatively little thought, attention or skill is impaired. At this stage, you may find you have to concentrate on opening a bottle of wine. Simply moving around in a crowd of people at a party may require your full attention. You may drop things and conversations may be difficult to follow.
As the alcohol level rises in the blood, muscular coordination is further affected and basic reflexes become progressively depressed. There is reduced hand steadiness, difficulty in standing and emotional outbursts. The drinker may become aggressive or hostile.
Beyond this stage, the drinker risks falling into a stupor and eventual coma. If the coma persists for more than 10 hours, a person usually dies of asphyxiation due to paralysis of the respiratory center of the brain. Alcohol poisoning usually occurs at BAC's above 400 mg%.
Effects of Alcohol
on Driving Performance The driving task has been described as a
complex divided attention task involving; 1) a central visual task (tracking
or maintaining the vehicle's lane position) and 2) a peripheral visual
task (scanning the environment, for objects, e.g. other traffic or potential
driving hazards). When these two activities are combined into a time-shared
or divided attention task, alcohol impairs driving performance at BAC's
as low as 50 mg%. Neither of the two activities appear to be impaired by
alcohol when performed alone. However, when combined, performance is generally
poorer on the peripheral visual task.
Alcohol impairment of performance in divided attention tasks is most likely due to an impairment of the information processing. It appears that alcohol has less effect on the processing of information from a single source than on that coming from several sources. Drivers who are under the influence of alcohol tend to concentrate on one task and neglect others in a divided attention task.
Driving an automobile is usually taken for granted as being a relatively easy task, not requiring much conscious effort or critical judgment. Yet the sensory functions of the body bombard the brain with required information which must be assimilated and processed such that smooth, controlled operation of the automobile results. The brain makes decisions and regulates motor activity based upon training and previous experiences. Thus, the many complete maneuvers that one makes while driving occurs "automatically" and one does not have to be consciously aware of it.
Because alcohol acts to depress the reticular activating system, several things occur. The altering mechanism is depressed such that a person does not become aware of potentially hazardous or dangerous situations that the sensory functions detect. The sensory functions themselves are deteriorated and may not be supplying complete or correct information to the brain. A person's motor of functions are impaired; yet, because of alcohol's depressant effect that person will feel less inhibited and more self confident about his driving skills. As a result a person, after having consumed alcohol, is more likely to speed into high risk situations which would normally be avoided or treated cautiously.
The Physiology of
Breath Testing Following oral consumption, alcohol is absorbed from
the gastro-intestinal tract and distributed throughout the body by the
circulatory system. Alcohol diffuses freely and is found in relative concentrations
according to the water content of the various tissues. By processes of
metabolism and simple excretion, including its passage into the breath,
alcohol is removed from the body.
The relative concentration of alcohol in the various tissues, including blood, urine, lachrymal fluid and saliva, can be predicted and correlated on the basis of their respective water contents. Alcohol passes unchanged from the blood stream into the breath and, therefore, the alcohol concentration of the blood may be calculated from a breath alcohol determination.
The process of respiration takes place at the juncture of the blood and the breath within the alveolar sacs, deep in the lungs. Blood coming from the right side of the heart is pumped through the pulmonary arteries which circulate through the alveolar region and carries with it carbon dioxide and other volatile gases which are produced in the body as a result of metabolism. These gases pass freely through the walls of the blood vessels in the alveoli. At the same time, oxygen from the breath diffuses through the alveolar walls to the blood stream. This process is concentration dependent, the gases diffuse from an area of higher concentration to an area of lower concentration. The pulmonary veins then carry the oxygen enriched blood from the lungs back to the left side of the heart where it is distributed throughout the body.
To conduct a proper breath analysis for alcohol content, it is necessary to sample breath from the deep lung region. A variety of techniques have been employed for this purpose but, generally, try to mimic the respiratory profile.
A variety of techniques have been employed to ensure the collection of a proper sample of breath, some of which rely upon operator judgment and training, while other techniques are completely automatic in their nature. One of the techniques is to provide a continuous and uninterrupted flow of breath above a minimum threshold pressure and for a minimum duration of time to a breath alcohol detector. This protocol ensures the sampling of deep lung air for the alcohol concentration necessary to the accuracy of of the breath testing instrument.