33.4 Effects of Drugs Effects of Drugs Section 33.4 How Drugs Work · drug - a substance, natural or artificial, that alters the function of the body ex. antibiotics, over-the-counter (OTC) pain relievers, cocaine, marijuana, caffeine · drugs that affect the nervous system... 1. increase amount of neurotransmitter released into synapse 2. prevent neurotransmitters from binding to a dendrite by blocking receptor site 3. prevent a neurotransmitter from leaving a synapse 4. imitate a neurotransmitter Dopamine · a neurotransmitter · involved with control of body movements and other functions, and with feelings of pleasure and reward "feel good" hormone · excess dopamine is reabsorbed by the neuron that released it · many drugs that affect the NS influence the level of dopamine Stimulants · drugs that increase alertness and physical activity · nicotine increases amount of dopamine released into synapse constricts blood vessel, raises blood pressure, makes heart work harder linked to lung cancer · caffeine - most commonly used binds to adenosine receptors on neurons in brain - adenosine slows down brain making you drowsy caffeine blocks adenosine and gives you a burst of energy temporarily raises epinephrine (adrenaline) levels Depressants · drugs that slow down NS, lower blood pressure, interrupt breathing, slow heart rate, relieve anxiety, make you sleepy · alcohol affects at least 4 neurotransmitters short-term effects - impairs judgement, coordination, reaction time long-term effects - reduction in brain mass, liver damage, stomach and intestinal ulcers, high blood pressure · inhalants - chemical fumes short-term effects - intoxication, nausea, vomiting, death long-term effects - memory loss, hearing loss, vision problems, nerve damage, brain damage Tolerance & Addiction · tolerance can lead to addiction · tolerance - need more of the same drug to get the same effect · addiction - physiological (body needs it) or psychological (you think you need it) dependence on a drug physiological - increased levels of dopamine in synapse (feelings of pleasure) quitting decreases dopamine levels (pleasing feeling leaves) psychological - use the drug for emotional reasons