Transcript Chapter 6

Chapter 6
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
Recirculation and Absorption


After leaving the lungs blood is pumped
from the left atrium, into the left ventricle,
then into the arteries which carries the
blood to all parts of the body
Alcohol moves from the blood to the tissues