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CHAPTER
40
THE NERVOUS SYSTEM AND THE EFFECTS OF DRUGS
Section 40.1 The Nervous System
Study the Diagram
Read the paragraph in the box and study the diagram. Then answer the questions.
The nervous system is like a very complicated computer. As in a computer, electrical signals
travel throughout the system. Instead of the wires you would see in a computer, the nervous system
is made up of nerve cells, or neurons. The neurons have gaps between them, called synapses,
which an electrical signal has to jump across in order to continue. Instead of jumping across the
gap as a spark, the impulse is passed across the gap by a chemical signal called a neurotransmitter.
Direction of impulse
Wire
Wire
Wire
Spark
Nerve
Neuron
Neuron
Synapse with neurotransmitters
1. What would happen to your nervous system if the neurotransmitters in your body were
The nervous system, including the brain, would stop
suddenly blocked? _________________________________________________________________
functioning. The neurotransmitters pass electrical impulses from one neuron to
__________________________________________________________________________________
the next across the synapse.
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2. What do you think would happen if a lot of neurotransmitters were suddenly placed throughout
all of your nervous system? __________________________________________________________
All of your nerve cells would fire at once.
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CHAPTER 40 BIOLOGY: The Dynamics of Life
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Neuron