For many years people have been aware of chemical substances that can change people's behavior
             by influencing their mood, their sensations, or their muscular coordination. These chemical, mind altering
             substances are known as psychoactive drugs (PaD). These PaD, depending on their cultures, were
             used for religious rituals to control pain, or to raise ones energy during warfare. As time went on, more
             and more people became aware of these substances and a familiar pattern started to form. People began
             using these chemical substances for pleasurable experiences.
             How do drugs work? For a drug to affect our behavior it has to get into our blood stream through
             ingestion, inhalation, absorption through the mucous membrane of the mouth or nose, or injection with a
             hypodermic needle. Once the PaD are in our bloodstream it starts to influence our behavior
             by altering the functioning of our central nervous system (CNS). After a period of hours, the drugs
             influence gradually wears off as the liver produces enzymes that metabolize the drug.
             Most PaD can be categorized into two major groups, stimulants (which enhance the
             activity of the CNS) and depressants (which slow down the activity of the CNS). By understanding how
             the drugs affect the action of the dopamine is one of the key elements to understanding drug addiction. It
             should also bring to your understanding how drugs affect our neurotransmitters. Drugs that mimic or
             facilitate the action of a particular neurotransmitter are called agonists. Drugs that block the action of a
             particular neurotransmitter are called antagonists.
             Stimulants are the PaD that speed up or enhance the activity of the CNS. Four very
             common stimulants are amphetamines, cocaine, nicotine, and caffeine. Here is a brief look at how they
             More concentrated forms of amphetamines (dextroamphetamine and methamphetamine, or
             "speed") are ...