Chapter 6. Toxicologist Detect and identify drugs and poisons in the body fluids, tissues, and organs and determine their influence on human behavior.

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