35–5 Drugs and the
Nervous System
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35–5 Drugs and the Nervous
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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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35–5 Drugs and the Nervous
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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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35–5 Drugs and the Nervous
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Drugs That Affect the Synapse
What are the different classes of drugs that
directly affect the central nervous system?
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35–5 Drugs and the Nervous
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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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35–5 Drugs and the Nervous
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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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35–5 Drugs and the Nervous
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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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35–5 Drugs and the Nervous
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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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35–5 Drugs and the Nervous
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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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35–5 Drugs and the Nervous
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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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35–5 Drugs and the Nervous
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Drugs That Affect the Synapse
Alcohol
What is the effect of alcohol on the body?
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35–5 Drugs and the Nervous
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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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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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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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35–5 Drugs and the Nervous
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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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A drug that increases the heart rate and
breathing rate is a
a. depressant.
b. opiate.
c. stimulant.
d. barbiturate.
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A powerful stimulant that increases blood
pressure and heart rate that can lead to a heart
attack is
a. cocaine.
b. opium.
c. marijuana.
d. caffeine.
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Many drugs that affect the brain and behavior do
so because they
a. affect organ systems and those changes are
detected by the brain.
b. interfere with the normal functioning of
neurotransmitters.
c. cause the brain to release endorphins.
d. enter the cell bodies of brain neurons
causing them to behave differently.
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True or False? Medically prescribed drugs
cannot cause addiction.
a. True
b. False
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Alcohol acts on the brain as a
a. general stimulant of the nervous system.
b. general depressant of the nervous system.
c. pain reliever acting in the cerebrum.
d. stimulant of the brain stem and cerebellum.
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