Chapter 6. Toxicologist Detect and identify drugs and poisons in the body fluids, tissues, and organs and determine their influence on human behavior.
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Toxicologist Detect and identify drugs and poisons in
the body fluids, tissues, and organs and determine their influence on human behavior.
Alcohol is the most heavily abused drug in Western countries.
40% of traffic deaths in the United States are alcohol related.
Toxicology of Alcohol Metabolism – all chemicals that enter the
body are eventually broken down by chemicals in the body into other chemicals which are easier to eliminate.
Three steps: absorption, distribution, and elimination
Absorption and Distribution Alcohol or ethyl alcohol is a colorless liquid
diluted with water and consumed as a beverage. Absorption – alcohol slowly enters the body’s
bloodstream and is carried to all parts of the body. Alcohol is distributed evenly throughout the watery
portions of the body. After absorption is completed a maximum alcohol level is
reached in the blood and the post absorption period begins.
Factors that affect rate of absorption:
Total time it takes to consume drink Alcohol content of the beverage Amount consumed Quantity and type of food present in the
stomach
Elimination
Alcohol is eliminated by oxidation and excretion Nearly all alcohol is oxidized or turned into carbon
dioxide and water in the liver The enzyme alcohol dehydrogenase is responsible
for this process. Alcohol is excreted unchanged by the breath, urine,
and perspiration. The amount of alcohol exhaled in the breath is in
direct proportion to the concentration of alcohol in the blood.
Blood alcohol concentration Blood is used because it circulates alcohol
throughout the body, carrying it to all tissues and the brain.
Blood alcohol concentration is directly proportional to concentration of alcohol in the brain.
Alcohol in the circulatory system You can measure alcohol present in the
blood stream by Analyzing the blood for alcohol content Measuring the alcohol content of the breath
Human circulatory system Humans have a closed circulatory system –
blood is carried inside the heart, arteries, capillaries, and veins. Artery – carries blood away from the heart Vein – carries blood back to the heart Capillaries – Tiny blood vessels that connect the
arteries with the veins
Ingestion and Distribution Alcohol is ingested Moves down esophagus into stomach 20% is absorbed through the stomach walls
into the portal vein of the blood system. Remaining alcohol passes into the blood
through the walls of the small intestine Blood carries the alcohol to the liver where it
is broken down
As the blood still carrying the alcohol leaves the liver it moves up to the heart.
It enters the right atrium and moves down to the right ventricle. It contains a lot of carbon dioxide and hardly any oxygen so the blood must go to the lungs to get more oxygen.
Aeration Pulmonary artery branches into capillaries lying
close to alveoli. Lungs contain about 250 million alveoli all located
at the end of bronchial tubes which connect to the windpipe which leads up to the nose and mouth
At the surface of the alveoli blood flowing through the capillaries comes in contact with fresh oxygenated air in the sacs.
Exchange of Oxygen and Carbon dioxide
Fresh air in the alveoli sacs exchange with spent air in the blood.
Oxygen passes from the alveoli into the blood Carbon dioxide is discharged from the blood into the air Alcohol will also pass from the blood into the alveoli The concentration of alcohol in the breath is equal to the
concentration of alcohol in the blood for a given temperature 1 ML of blood contains nearly the same amount of alcohol as
2100 ML of breath
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