The nervous system is the control system and the network of communication for the body. The nervous system is made up of nerves, the spinal cord and the brain. The nerves control everything we do; they carry messages that tell us to move, to breathe, to feel and to think. Nerves run to the muscles, organs, heart, lungs, blood vessels, brain--even to our teeth and skin. There are two sets of nerves: the central nervous system and the peripheral (outside) nervous system.

The central nervous system is made up of the brain and spinal cord. The peripheral (outside) nervous system is all the other nerves in the body. The nerves are very close together. Special chemicals called neurotransmitters carry messages from one nerve to the next nerve. Drugs affect the body by changing the neurotransmitters in the nerves. A nerve looks like this:

Nerve transmitters (Neurotransmitters)

The nerves contain chemicals called neurotransmitters. As their name suggests, neurotransmitters "transmit" or "carry" messages from one nerve to another. 

The space between each nerve is called the synapse. The transmitters travel across this synapse to get messages to the brain or out to the body. The transmitters have names like dopamine, epinephrine (adrenaline), norepinephrine and seratonin.

These transmitters are changed by drugs. Drugs can speed up, slow down or confuse the transmitters. Different drugs affect different transmitters. Drugs that cause transmitters to be released speed up the body and the brain. Drugs that cause the transmitters to become confused also confuse the body and the brain. Drugs that block the transmitters slow down the body and the brain. The neurotransmitters are very important. When these transmitters are changed by drugs, all the problems begin.

Drugs affect the body by changing the neurotransmitters.

The Peripheral Nerves

The peripheral nerves run from the spinal cord to all parts of the body. They surround all the organs, muscles and tissues--the heart, liver, intestines, lungs, skin and blood vessels. 

The peripheral nerves pick up information about the body and send messages through the spinal cord to the brain. The brain sends out messages to the peripheral nerves so they may control our actions. These outside nerves receive messages from the brain and control the heartbeat, blood pressure, breathing and all of the body functions. The transmitter chemicals carry all of the messages between the nerves.

The Central Nervous System

The central nervous system is made up of the spinal cord and the brain. The spinal cord is located in the middle of the back and connects the nerves in the body to the brain.

Think of your brain as a great message center. Imagine a system so complex that it can take in and send out millions of messages every second. The brain controls everything we do. Messages from the brain control our thoughts, breathing and heart rate.

Inside the brain, groups of nerves make up brain centers, which control different things. The brain has a "pleasure center" that makes us feel happy or sad. The brain has a "hunger center" that tells us if we are hungry or full. It is important to remember that the brain centers send out messages to the outside nerves. The respiratory center in the brain controls breathing, and the nerves around the lungs also control breathing--both nervous systems work together. The brain centers are affected by drugs.

For example, cocaine affects the "hunger center." Cocaine makes the brain think the body is not hungry and does not need to eat. Thatís why people who use cocaine often lose weight and look sick. Drugs affect the brain. The brain does not work the way it should when it is on drugs.

Drugs that increase blood pressure to the brain cause strokes. A stroke occurs when a blood vessel bursts or is blocked in the brain. When blood doesn't reach the brain, that area of the brain dies. Many times this causes parts of the body to become paralyzed (not able to move).

The different parts of the brain control different areas of the body, and where and how much brain is damaged will determine where and how much the body is paralyzed. A stroke will often paralyze an entire half of the body. Many young people have had strokes caused by using amphetamines and cocaine, and they are now paralyzed.

The problem with drugs begins when the nerves and brain get used to drugs being in the body. The brain can become addicted to drugs. Addiction means the brain likes something and tells the body to do more and more of it.

Another problem that results from drug use is tolerance. Tolerance occurs when the body and brain get used to the drug. The brain asks for larger amounts of drug to feel an effect and this can lead to an overdose. An overdose happens when too much drug is taken at one time. An overdose makes the body sick, and usually causes death.

The body becomes used to drugs or dependent on drugs, and the body goes through "withdrawal" when it doesnít get these drugs. Withdrawal can be very painful. During drug withdrawal, the body craves the drug it has become used to, and when it doesnít get the drug, the body gets sick.

Thatís why so many people today donít even want to try drugs. They know itís easier to stay away from drugs than to withdraw from them after they have become addicted.

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