Topic: Nervous System
Aim: Use textual evidence to describe the structure of neurons.
Directions: Read the passage below and use textual evidence to answer questions 1-14.
Neurons transmit impulses throughout the body. An impulse is both electrical and chemical in nature. Impulses travel
along nerve cells, called neurons.
The central cell body is the largest part of a neuron and contains the neuron's nucleus, associated cytoplasm, and other
cell structures. The cell body produces proteins needed for the construction of other parts of the neuron.
Dendrites typically carry impulses toward the cell body. Dendrites are usually more numerous, shorter and more branched
than axons. Axons typically carry impulses away from the cell body. Some axons are wrapped with Schwann cells. These cells
form the myelin sheath, which indirectly assists in the conduction of impulses as myelinated nerves can conduct impulses
quicker than unmyelinated ones.
Nerve impulses are received at the neuronal dendrites and are carried along the axon to the terminal branches.
These branches end at a junction, or space, called a synapse. It is at the synapse where impulses must cross the gap
and be carried to the dendrites of adjacent cells. At synapses, chemical signals called neurotransmitters are released
by the terminal branches, which cross the gap junction to stimulate the next neuron
1. Describe the nature of an impulse.
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2. Use the information from the reading to label the neuron diagram below (dendrites, cell body, axon, Schwann cell, terminal
branches)
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3. Identify the first part of the neuron that receives the electrical impulse? _________________________________________
4. Identify the largest part of the neuron. ____________________________________________________________________
5. Identify three cell parts located in the cell body. ____________________________________________________________
6. Identify the longest part of the neuron. ____________________________________________________
7. Identify the substance that can surround some axons. __________________________________________________
8. Describe the benefit of axons wrapped by Schwann cells. _____________________________________________________
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9. Identify the branches at the end of the neuron. ____________________________________________________
10. Identify the gap between neurons. ___________________________________________________
11. Identify the chemical released by terminal branches into the synapse. __________________________________________
12. Describe the function of neurotransmitters. ________________________________________________________________
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13. For each part of the neuron, identify whether the impulse is electrical or chemical?
a. Dendrites: __________________________
d. Terminal branches: __________________________
b. Cell body: __________________________
e. Synapse __________________________
c. Axon: __________________________
14. Write the correct sequence of structures the impulse travels when moving through a neuron.
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