Most of the drugs that people abuse have their effect on the limbic system of the brain. The limbic system is located deep within the brain near the top of the brain stem. The limbic system produces the feelings of pleasure, pain, anger, and fear which characterize our emotions. All drugs of addiction work on our emotions. If a certain drug makes us feel very good, we tend to want to take that drug again and again. It is because of this temporary good feeling that we become psychologically addicted to a drug.
Within the limbic system, drugs work on the brain by way of neurotransmitters. Neurotransmitters are the chemicals which allow our nerve cells to communicate with each other. Some of the neurotransmitters affected by drugs are serotonin, norepinephrine and dopamine. The class of drugs called stimulant drugs will usually make more a neurotransmitter(s) available to the brain.
The class known as depressant drugs will usually make less of a neurotransmitter(s) available to the brain. Because our brain adjusts to this alteration in neurotransmitters, our brain may become physiologically (physically) dependent on some drugs. Although our brain can become physiologically dependent on a wide variety of drugs, the brain is more likely to become dependent on depressant drugs than on stimulant drugs.
As drugs appear in nature they can be addictive. However, it is technology which makes them very addictive. Opium, a drug which occurs naturally in the white poppy plant, is classed as a narcotic. A narcotic drug relieves pain and induces sleep. The brain has neurotransmitters which controls our perception of pain. These neurotransmitters are called endorphins. Within the brain, endorphins mask pain and make us feel good. All opium products are chemically similar to endorphins and have their pleasurable effects by substituting for endorphins in...