10.2 Notes – Toxicology continued

1. 10.2 Notes – Toxicology continued

2. 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

3. 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

4. Breakdown of alcohol in the body • r • 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

5. 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

6. 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

7. 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

8. 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

9. 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?