The neurotransmitters are affected by the drug once in the brain. Neurotransmitters control the movement of information within the brain between the brain cells, creating a synapse. Neurotransmitters also change a person’s mood and feelings, for example they can be happy one minute then angry the next. Different drugs do different things to the neurotransmitters. Some cause the neurotransmitters to produce more serotonin making the person feel euphoric, or happy. Other drugs lower the levels of serotonin in the brain and make the person have depression temporarily or even permanently. While certain drugs make a person feel extra happy, they have a crash, or when they are coming down from the drug. The brain can only produce a certain amount of serotonin at a time and the more the drug demands the less the person will have when off the drug causing the depression, suicidal thoughts, etc.
Once drugs are entering the bloodstream the heart pumps that blood containing the drug to the brain where it will affect how people react. Some drugs can weaken the heart's ability to pump blood and this causes heart failure. Also they can increase the chances if a person having heart attacks. A common drug that does this is alcohol. Drugs like alcohol and ecstasy also damage the liver causing cirrhosis, which can be deadly.
The lungs are affected greatly by drugs. Anything that is inhaled enters the blood and the brain very rapidly. Examples of this are drugs that are normally snorted or injected but are crushed up more or changed to make them smokeable, like cocaine into crack and amphetamine into methamphetamine. The lungs have the capability to absorb large amounts of drugs in a short amount of time and this makes the effects almost instant and very potent.
Another dangerous choice of drugs is inhalants. Inhalants can cause permanent damage to the lungs, suffocation or overdosing, due to the drugs clogging the bronchioles. This is similar to an asthma suffer taking their asthma medicine as the results are almost instant. Most people who do inhalants like aerosol cans and whip cream cans are asthma sufferers and they’re almost definite to result in a fatality.
Drugs numb the nervous system; this is why some people take them to temporally get rid of feelings. Before they know it drugs will make a person less aware of what is going on around him and he will not be as quick to think or react. This can make a person more susceptible to get into accidents.
Another affect drugs have on the body is addiction. The nerve cells get accustomed to having the drug and they feel like they need it to work normally. When a person is not taking the drug, after using it a lot, symptoms in the brain and body become