Download Study/Review * Nervous System Part 2 * CNS and PNS

Biology 102 Nervous System: Neurons, Nerve Impulse, and Neurotransmitters
Study Guide and Review
Match the following terms with statements below. Make up your own statement for terms
that are not used.
A.
B.
C.
D.
E.
Dendrites
Axon
Sensory neurons
Interneurons
Motor neurons
F. Astrocyte
G. Oligodendrocyte
H. Schwann cells
I. Microglia
J. Effector
K. Neuroglia
L. Myelin sheath
_____ General term for cells that nourish and support neurons
__E___ Gland or muscle cell
_____ Cells that eat foreign material (phagocytic cells)
__A___ Short extensions that carry impulses to the cell body of the neuron
_____ Neurons in the CNS only
_____ Protective and insulating “jelly roll” on axons of PNS and CNS
__B__ Long extension that carries impulses away from the cell body
__C___ Take nerve impulses from a sensory receptor to the CNS
_____ Cells that provide nutrients and hormones for neurons
_____ Take impulses from CNS to effectors
_____ Cells that make myelin sheath in the PNS
Fill in the blank:
1. Chemicals stored at the ends of axons and responsible for transmission of an impulse across
the synaptic cleft are called ____________________________
2. These cells make myelin on axons of the CNS: _______________________
3. _________________________ are gaps in the myelin sheath
4. A change in ion/charge distribution across the axon membrane is called
___________________________
5. ___________________is a region between an axon terminal and a dendrite or cell body of
another neuron
6. The name of an autoimmune demyelination disease characterized by antibodies to myelin is
_________________________________
Nerve Impulses – Give a brief description of what happens when a nerve is resting and when
there is a nerve impulse by filling in the table below. Include the following information:
o Voltage (positive or negative) – as would be measured by a volt meter
o Charge distribution – inside and outside of the axon membrane
o What are the conditions that result in the stated charge distribution/voltage
with respect to sodium/potassium ions
Condition
Voltage
(+ or -)
Charge
outside
axon
membrane
Charge
inside
axon
membrane
No impulse
(resting)
‘polarization’
Nerve impulse
Depolarization
Nerve impulse
Repolarization
No impulse
(resting)
‘polarization’
Compare myelinated vs. non-myelinated axons:
a) Speed of the impulse
b) What is the role of myelination?
Why? How?
Synapses
Draw a synapse and label major parts:
Word Bank: presynaptic membrane, synaptic cleft (gap), postsynaptic membrane,
neurotransmitter in vesicles, receptors
How does the nerve impulse get across the gap?
What is the role of calcium at the synapse?
Tell what happens (step by step) at a synapse. What is the difference between excitation and
inhibition?
Practice with multiple choice:
1. Which of the following is not a neurotransmitter?
a. Serotonin
b. Norepinephrine
c. Acetylcholine
d. Dopamine
2. Antidepressants like Prozac act by
a. Looking like a receptor for neurotransmitters
b. Causing excitation of ‘happy’ neurons
c. Preventing reabsorption of neurotransmitters
d. Preventing degradation of neurotransmitters
3.
What type of neuron lies completely in the CNS?
a. Motor
b. Interneurons
c. Sensory
4. Neuroglial cells forming myelin sheaths in the PNS are
a. Oligodendrocytes
b. Ganglionic cells
c. Schwann cells d. Microglia
5. Which of these correctly describes the distribution of ions on either side of an axon when it
is not conducting a nerve impulse?
a. More sodium ions outside and more potassium ions inside
b. More potassium ions outside and less sodium ions inside
c. Charged proteins outside and sodium and potassium ions inside
d. Sodium and potassium ions inside and water only inside
6. When the action potential begins, sodium gates open, allowing sodium ions to cross the
membrane. Now the polarity changes to
a. Negative outside and positive inside
b. Positive outside and negative inside
c. Neutral outside and positive inside
d. Neutral inside and positive outside
7. Repolarization of an axon during an action potential is produced by
a. Inward diffusion of sodium ions
b. Outward diffusion of potassium ions
c. Inward active transport of sodium ions
d. Active extrusion of potassium ions
8. Transmission of the nerve impulse across a synapse is accomplished by the
a. Movement of sodium and potassium ions
b. Release of a neurotransmitter by a dendrite
c. Release of a neurotransmitter by an axon
d. Release of a neurotransmitter by a cell body
9. Synaptic vesicles are
a. At the ends of dendrites and axons
b. At the ends of axons only
c. Along the length of all long fibers
d. All of these are correct
10. What mechanism is responsible for maintaining the unequal distribution of Na+ and K+ ions
across the membrane of an axon?
a. Nodes of ranvier
c. Sodium-potassium pumps
b. Gated ion channels
d. Osmosis
11. What term is used to describe how an action potential ‘jumps’ down a myelinated axon?
a. Saltatory conduction
c. Osmosis
b. Schwann cell conduction
d. Refractory period
12. What ion is critical for the release of neurotransmitters at a synapse?
a. H+
b. Na+
c. K+
d. Ca++
13. When an action potential begins, what causes the depolarization of the axon?
a. A rush of Na+ out of the axon
c. A rush of Na+ ions into the axon
b. A rush of K+ ions out of the axon
d. A rush of K+ ions into the axon