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Alcohol Interlock
Curriculum:
Legal Concerns
Alcohol and the human body
 Offenders may challenge the accuracy of breath test
readings captured by the alcohol interlock.
 For this reason, it is important that program authorities
have a good understanding of how alcohol is
metabolized by the human body.
 “Alcohol” is the name of a family of closely-related and
naturally-occurring chemicals.
Alcohol and the human body
 Ingestible alcohol is known as ethyl alcohol
or ethanol.
 Ethanol is a central nervous system
depressant.
 It does not affect a person until it reaches a
person’s central nervous system (e.g., the
brain, brain stem and spinal cord).
 Ethanol reaches the brain through the blood.
Alcohol and the human body
 Absorption of alcohol.
• Alcohol can be ingested in a variety of ways. In most
cases, it is ingested orally.
• Drinking on an empty stomach creates an ideal
circumstance for rapid absorption.
• When alcohol gets into an empty stomach, about 20%
of it will make its way directly through the walls of the
stomach.
• The remaining 80% will pass directly through the
stomach into the lower intestine from where it is readily
absorbed into the blood.
Alcohol and the human body
 Absorption of alcohol.
• When the brain senses food in the stomach, it
commands a small muscle at the base of the
stomach (the pylorus or pyloric valve) to cut off the
passage of the stomach contents to the small
intestine.
• Food and any alcohol remain trapped in the
stomach.
• Some of this alcohol will begin to break down
chemically.
• For this reason, a drinker’s BAC will not climb as
high as it would have if he or she had been drinking
on an empty stomach.
Alcohol and the human body
 Distribution.
• Alcohol has an affinity for water but is less soluble in fat.
• Once in the blood, alcohol is distributed throughout the body
in proportion with water content.
• Research shows that there are some important differences
in the way that alcohol is distributed in men and women.
• A Swedish pioneer in alcohol research, E.M.P. Widmark,
determined that the typical male body is about 68% water;
the typical female body has only about 55% water.
• As a result, when a man and a woman drink exactly the
same amount of alcohol under the same circumstances, the
woman’s BAC will be higher.
Alcohol and the human body
 Elimination of alcohol.
• As soon as alcohol enters the bloodstream the
body starts to rid itself of the alcohol.
• Some alcohol (about 2-10%) is expelled by the
body in a person’s breath, urine, sweat, and tears.
• The majority of alcohol is eliminated through the
process of metabolism. Alcohol reacts with oxygen
in the body and changes into carbon dioxide and
water both of which are directly expelled from the
body.
Alcohol and the human body
 Elimination of alcohol.
• Most of the metabolizing of the alcohol takes place
in the liver.
• The speed of this reaction varies somewhat from
person to person, and even from time to time for
any given person. On average, a person’s BAC
will drop by about 0.015 per hour.
• There is nothing that can be done to speed up the
metabolism or the process of elimination. Drinking
coffee, exercise, deep breathing or a cold shower
will NOT speed up the elimination process.