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# 22.1: The Nervous System

Difficulty Level: At Grade Created by: CK-12

## Lesson 22.1: True or False

Name___________________ Class______________ Date________

Write true if the statement is true or false if the statement is false.

_____ 1. An action potential is necessary for a nerve impulse to occur.

_____ 2. Sensory neurons carry nerve impulses from the brain and spinal cord to muscles and glands.

_____ 3. The peripheral nervous system includes the brain and spinal cord.

_____ 4. The myelin sheath is similar to the plastic that encases an electrical cord.

_____ 5. The somatic nervous system controls the reactions necessary to write “true” or “false.”

_____ 6. The sensory division of the CNS includes the eyes, ears, mouth, nose, and skin.

_____ 7. The spinal cord is the most complex organ of the human body and the control center of the nervous system.

_____ 8. Taste buds on the tongue are actually found in taste receptor cells.

_____ 9. All psychoactive drugs are illegal.

_____ 10. Balance is due to an interaction between your hearing and vision receptors.

_____ 11. Neurotransmitters are molecules that cross the synapse.

_____ 12. The peripheral nervous system includes the sensory division and the motor division.

_____ 13. The cerebrum is the largest part of the brain.

_____ 14. The reason you can smell your food is because of the taste buds in your nose.

_____ 15. Dendrites extend from the cell body and send nerve impulses to other neurons.

## Lesson 22.1: Critical Reading

Name___________________ Class______________ Date________

Read these passages from the text and answer the questions that follow.

Nerve Cells

Although the nervous system is very complex, nervous tissue consists of just two basic types of nerve cells: neurons and glial cells. Neurons are the structural and functional units of the nervous system. They transmit electrical signals, called nerve impulses. Glial cells provide support for neurons. For example, they provide neurons with nutrients and other materials.

Neuron Structure

As shown in the FlexBook, a neuron consists of three basic parts: the cell body, dendrites, and axon. You can watch an animation of the parts of a neuron at this link: http://www.garyfisk.com/anim/neuronparts.swf.

• The cell body contains the nucleus and other cell organelles.
• Dendrites extend from the cell body and receive nerve impulses from other neurons.
• The axon is a long extension of the cell body that transmits nerve impulses to other cells. The axon branches at the end, forming axon terminals. These are the points where the neuron communicates with other cells.

Myelin Sheath

The axon of many neurons has an outer layer called a myelin sheath. Myelin is a lipid produced by a type of a glial cell known as a Schwann cell. The myelin sheath acts like a layer of insulation, similar to the plastic that encases an electrical cord. Regularly spaced nodes, or gaps, in the myelin sheath allow nerve impulses to skip along the axon very rapidly.

Types of Neurons

Neurons are classified based on the direction in which they carry nerve impulses.

• Sensory neurons carry nerve impulses from tissues and organs to the spinal cord and brain.
• Motor neurons carry nerve impulses from the brain and spinal cord to muscles and glands.
• Interneurons carry nerve impulses back and forth between sensory and motor neurons.

Questions

1. What is a neuron? What are glial cells?

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2. What is the role of a dendrite and an axon?

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3. What does the myelin sheath do?

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4. Describe the three types of neurons.

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## Lesson 22.1: Multiple Choice

Name___________________ Class______________ Date________

Circle the letter of the correct choice.

1. Neurons transmit electrical signals called
1. nerve signals.
2. nerve impulses.
3. nerve potential.
4. axon impulses.
2. The parts of a neuron include
1. the cell body.
2. one axon.
3. numerous dendrites.
4. all of the above.
3. What is an action potential?
1. An action potential is a sudden reversal of the electrical charge across the membrane of a resting neuron.
2. An action potential is a sudden reversal of the electrical charge across the membrane of an active neuron.
3. An action potential is a slow reversal of the electrical charge across the membrane of a resting neuron.
4. An action potential is a sudden reversal of the chemical charge across the membrane of a resting neuron.
4. At the synapse,
1. neurotransmitter molecules travel across the axon terminals and bind to receptors on the membrane of the other cell.
2. neurotransmitter molecules travel across the axon terminals and bind to vesicles on the membrane of the other cell.
3. neurotransmitter molecules travel across the synaptic cleft and bind to receptors on the membrane of the other cell.
4. neurotransmitter molecules travel across the synaptic cleft and bind to signal proteins on the membrane of the other cell.
5. The largest part of the human brain is the
1. cerebellum.
2. cerebrum.
3. frontal lobe.
4. brain stem.
6. Your somatic nervous system is responsible for
1. involuntary activities not under conscious control.
2. emergency situations.
3. the organs of your digestive system.
4. voluntary activities that are under conscious control.
7. Alzheimer’s disease most likely occurs when
1. nervous tissue degenerates.
2. nervous tissue may become infected by microorganisms.
3. there are problems with blood flow.
4. there are brain or spinal cord injuries.
8. Your sense of balance is the responsibility of
1. your eyes.
2. your ears.
3. both your eyes and ears.
4. your sense of touch.
9. The peripheral nervous system consists of
1. all the nervous tissue that lies outside the central nervous system.
2. your brain and spinal cord.
3. all your neurons and axons.
4. all of the above.
10. The central nervous system consists of
1. all the nervous tissue that lies outside the central nervous system.
2. just your brain.
3. just your spinal cord.
4. your brain and spinal cord.

## Lesson 22.1: Vocabulary I

Name___________________ Class______________ Date________

Match the vocabulary word with the proper definition.

Definitions

_____ 1. electrical signal transmitted by the neurons

_____ 2. carry nerve impulses from the brain and spinal cord to muscles and glands

_____ 3. difference in electrical charge when a neuron is not actively transmitting a nerve impulse

_____ 4. the place where an axon terminal meets another cell

_____ 5. acts like a layer of insulation

_____ 6. carry nerve impulses from tissues and organs to the spinal cord and brain

_____ 7. consists of all the nervous tissue that lies outside the central nervous system

_____ 8. structural and functional unit of the nervous system

_____ 9. molecules that travel across the synaptic cleft and bind to receptors on the membrane of the other cell

_____ 10. carry nerve impulses back and forth between sensory and motor neurons

_____ 11. a sudden reversal of the electrical charge across the membrane of a resting neuron

_____ 12. includes the brain and spinal cord

_____ 13. a cable-like bundle of axons

_____ 14. part of the neuron that contains the nucleus and other cell organelles

_____ 15. extends from the cell body and receives nerve impulses from other neurons

_____ 16. a long extension of the cell body that transmits nerve impulses to other cells

Terms

a. action potential

b. axon

c. cell body

d. central nervous system

e. dendrite

f. interneuron

g. motor neuron

h. myelin sheath

i. nerve

j. nerve impulse

k. neuron

l. neurotransmitter

m. peripheral nervous system

n. resting potential

o. sensory neuron

p. synapse

## Lesson 22.1: Vocabulary II

Name___________________ Class______________ Date________

Fill in the blank with the appropriate term.

1. ____________ are the structural and functional units of the nervous system.

2. A nerve impulse travels down an axon membrane as an electrical ____________ potential.

3. Human senses include sight, hearing, balance, taste, smell, and ____________.

4. ____________ are chemicals that affect the body’s structure or function.

5. The ____________ are also responsible for the sense of balance.

6. Sensory nerves carry nerve impulses from ____________ to the central nervous system.

7. The____________ nervous system controls mainly voluntary activities that are under conscious control.

8. Neurons consist of a cell body, ____________, and axon.

9. A nerve is a cable-like bundle of ____________.

10. ____________ is use of a drug without the advice of a medical professional and for reasons not originally intended.

11. The ____________ is protected by the vertebrae.

12. The place where an axon terminal meets another cell is called a ____________.

13. ____________ drugs affect the central nervous system.

14. The central nervous includes the brain and ____________.

15. The ____________ is a long extension of the cell body that transmits nerve impulses to other cells.

## Lesson 22.1: Critical Writing

Name___________________ Class______________ Date________

Thoroughly answer the question below. Use appropriate academic vocabulary and clear and complete sentences.

An action potential can be referred to as a “wave of depolarization” down the axon. Explain what you think this means.

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Date Created:
Feb 23, 2012
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Aug 16, 2016
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CK.SCI.ENG.WB.1.Biology.22.1