1. 35–5 Drugs and the Nervous System
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A drug is any substance, other than food, that changes the structure or function of the body.
Some drugs, such as cocaine and heroin are illegal. Other drugs, such as penicillin and codeine are prescribed by doctors. Still other drugs, including cough medicines can be purchased over the counter.
All drugs can be harmful if used improperly or abused.
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Drugs differ in the ways in which they affect the body.
Some kill bacteria and are useful in treating disease.
Others affect a particular system of the body.
Others cause changes to the brain and synapses.
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4. Drugs That Affect the Synapse
What are the different classes of drugs that directly affect the central nervous system?
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5. Drugs That Affect the Synapse
Stimulants
Stimulants increase heart rate, blood pressure, and breathing rate. In addition, stimulants increase the release of neurotransmitters at some synapses in the brain.
Common stimulants include amphetamines, cocaine, nicotine, and caffeine.
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6. Drugs That Affect the Synapse
Depressants 
Depressants slow down heart rate and breathing rate, lower blood pressure, relax muscles, and relieve tension.
Barbiturates, tranquilizers, and alcohol are some examples of depressants.
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7. Drugs That Affect the Synapse
Cocaine  
Cocaine causes the sudden release in the brain of a neurotransmitter called dopamine.
Cocaine also acts as a powerful stimulant.
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8. Drugs That Affect the Synapse
Opiates  
Opiates mimic endorphins which normally help to overcome sensations of pain.
Common opiates include morphine and codeine.
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9. Drugs That Affect the Synapse
Marijuana
The most widely abused illegal drug is marijuana.
Marijuana comes from Cannabis sativa, a hemp plant.
Hashish, or hash, is a potent form of marijuana.
The active ingredient in marijuana is THC.
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10. Drugs That Affect the Synapse
Long-term use of marijuana can result in:
loss of memory
inability to concentrate
in males, reduced levels of the hormone testosterone in males
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11. Drugs That Affect the Synapse
Alcohol
What is the effect of alcohol on the body?
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12. Drugs That Affect the Synapse
Alcohol is a depressant that slows down the rate at which the central nervous system functions.
Alcohol slows down reflexes, disrupts coordination, and impairs judgment.
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13. Drugs That Affect the Synapse
Heavy drinking fills the blood with so much alcohol that the central nervous system cannot function properly.
People who drink a lot of alcohol usually cannot walk or talk properly, and they are not able to safely control an automobile.
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14. Drugs That Affect the Synapse
Pregnant women who drink alcohol risk having a child with FAS.
Fetal alcohol syndrome (FAS) is a group of birth defects caused by the effects of alcohol on the fetus.
FAS can cause minor to serious brain damage, heart defects, malformed faces, delayed growth, and poor motor development.
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15. Drugs That Affect the Synapse
Alcohol and Disease
People who have become addicted to alcohol suffer from a disease called alcoholism.
If a person cannot function properly without satisfying the craving for alcohol, that person has an alcohol-abuse problem.
Long-term alcohol use destroys liver cells.
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Drug Abuse
Drug Abuse
Drug abuse is the intentional misuse of any drug for nonmedical purposes.
Drug abuse can cause psychological dependence or serious physical damage to the body.
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Drug Abuse
Uncontrollable dependence on a drug is called an addiction.
Some drugs cause a strong psychological dependence, or mental craving.
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35–5
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35–5
A drug that increases the heart rate and breathing rate is a
depressant.
opiate.
stimulant.
barbiturate.
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35–5
A powerful stimulant that increases blood pressure and heart rate that can lead to a heart attack is
cocaine.
opium.
marijuana.
caffeine.
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35–5
Many drugs that affect the brain and behavior do so because they
affect organ systems and those changes are detected by the brain.
interfere with the normal functioning of neurotransmitters.
cause the brain to release endorphins.
enter the cell bodies of brain neurons causing them to behave differently.
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35–5
True or False? Medically prescribed drugs cannot cause addiction.
True
False
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35–5
Alcohol acts on the brain as a
general stimulant of the nervous system.
general depressant of the nervous system.
pain reliever acting in the cerebrum.
stimulant of the brain stem and cerebellum.
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