NERVOUS
SYSTEM
Neurons
1. Read
"Neuron Structure" p. 318. Identify the following parts of a motor
neuron from fig. 17.2 and describe these parts below:
a. cell body
b. dendrite
c. axon
d. node of
Ranvier
e. myelin
sheath
f. synaptic
endings
2. There are
three types of neurons found in the nervous system. It is important to
understand their function, the location, and direction of impulse. Fill in the
chart below.
|
Type of
Neuron |
Structure |
Direction
of Impulse |
Function |
|
sensory
neuron |
|
|
|
|
interneuron |
|
|
|
|
motor
neuron |
|
|
|
3. Define
the term neuron.
Impulse
Generation (pp. 320 - 321)
1. Define
the following terms:
a. impulse
b. resting
potential
c. action
potential
2. What is
meant when we say that a neuron has:
a. a resting
potential
b. an action
potential
3. A neuron
has a resting potential. Referring to the distribution of ions, explain why the
neuron is positive on the outside and negative on the inside.
4. What
maintains the distribution of ions outside and inside the neuron?
5. A neuron
is having an action potential. What events occur during the action potential?
6. Explain
why the neuron becomes more positive on the inside during an action potential.
7. Explain
what happens when a neuron is:
a.
depolarized
b. polarized
8. Explain
how a nerve impulse is transmitted along a neuron using the term resting
potential and action potential.
9. Explain
why neurons carry an impulse (action potential) in only one direction.
10. Explain
why a myelinated neuron transmits impulses faster than a nonmylinated neuron.
11. Define
the following terms:
a. recovery
period
b. "all
or none response"
Synapse (pp. 322 - 323)
1. Using
fig. 25.9, and the text on pages 306-307, state the function of the listed
components of a synapse:
a. axon
b. synaptic
ending
c.
presynaptic membrane
d. synaptic
vesicles
e. synaptic
cleft
f.
neurotransmitter substances
g.
postsynaptic membrane
h. dendrite
2. Explain
how a nerve impulse crosses a synapse. Use the following headings to list your
main points.
a. pathway
the impulse takes to get to the end of the neuron
b. events
that occur when impulse reaches the synaptic ending
c. role of
the calcium ions
d.
neurotransmitters-their action and role
e. role of
the cleft
f.
excitation of postsynaptic membrane
g. short
existence of neurotransmitters in the synapse
h. acetylcholine
Reflex
Arc (pp. 335)
1. Describe
the function of a reflex arc.
2. Identify
the labeled parts of a reflex arc on fig. 17.16 p. 335 and state the function
of each.
a. receptor
b. sensory
neuron
c.
interneuron
d. motor
neuron
e. effector
organ
3. Trace the
pathway through a reflex arc starting with the stimulation of a skin receptor
and ending at the effector organ. List the events a, b, c, ... etc.
Sample
Exam Questions
1. Describe
the events that occur during a synapse transmission.
2. Name the
main components of a reflex arc and describe the passage of an impulse through
this arc.
3. Explain
how an impulse passes along a motor neuron.
4. Compare and contrast an action potential with a resting potential.