Psychoactive Drugs:These are chemical substances that alter perception, mood or consciousness. They include stimulants like caffeine and depressants like alcohol.
Pharmacokinetics: The study of what happens to a drug from when it enters until it leaves your body - absorption into bloodstream; distribution around body; metabolism into different substances; excretion out of body.
Pharmacodynamics: This is the study of how drugs affect our bodies. It looks at the biochemical and physiological effects of drugs and their mechanisms of action.