10.2 Notes – Toxicology continued

Objectives Explain how alcohol is absorbed into the bloodstream, transported throughout the body, and eliminated by oxidation and excretion. Understand the process by which alcohol is excreted in the breath via the lungs

Breakdown of alcohol in the body Oxidation – occurs in the liver using dehydrogenase to convert alcohol to acetaldehyde and then to acetic acid to carbon dioxide and water

Breakdown of alcohol in the body Excretion – breath, urine, perspiration Amount of alcohol exhaled in the breath is in direct proportion to concentration in the blood Elimination rate - .015 percent weight/per volume per hour

Alcohol in the Circulatory System Measuring the quantity in the blood stream Direct chemical analysis of the blood Measurement of the alcohol content in the breath uses Henry’s Law

Henry’s Law When alcohol is dissolved in blood and brought to equilibrium with alveolar breath, the fixed ratio between the concentration of alcohol in alveolar air and blood is constant for a given temperature (approximately 34 degrees C.) Evidence shows alcohol in blood to alcohol in air 2,100 to 1: 1 mL of blood will contain the same amount of alcohol as 2,100 mL of alveolar breath

Circulatory System Closed Basically heart and numerous arteries, capillaries, and veins Artery = blood vessel carrying blood away from heart Vein = vessel carrying blood back to heart Capillary = tiny blood vessels that interconnect the arteries and veins

Lungs = bridges the respiratory system to the circulatory system Alveoli = tiny pear-shaped sacs About 250 million in lungs All located at the end of bronchial tubes At the surface of alveolar sacs blood flows and comes in contact with oxygenated air Alcohol and other substances in blood will pass into alveoli

10.2 Questions – answer on notebook paper List and describe the three stages of alcohol’s fate in the human body. About 95-98% of alcohol is oxidized into what two substances? Carbon dioxide and dehydrogenase Water and acetic acid Acetaldehyde and acetic acid Water and carbon dioxide Alcohol that is not oxidized is expelled unchanged in what bodily excretions? The amount of alcohol exhaled in the breath is in direct proportion to what? From the medicolegal point of view, what is the accepted standard for relating alcohol intake to its effects on the body? List and describe the functions of the three types of blood vessels in the circulatory system. Through the walls of which organ is most alcohol absorbed into the bloodstream? In what other organ does the remainder of the absorption occur? When the blood enters the lung region from the heart, what are the relative levels of oxygen and carbon dioxide? What are alveoli and what role do they play in circulation? What is the most widespread method for rapidly determining alcohol intoxication? What scientific observation forms the theoretical basis for breath testing?