BIOLOGY II
NERVOUS SYSTEM
ACTIVITY #2
NAME_____________________
DATE___________HOUR_____
NERVE IMPULSE T RANSMISSION
OBJECTIVES:
4.
5.
Explain how nerve impulses are generated and how they are conducted
along a nerve fiber (pp. 200 – 224)
Describe the mechanism of nerve impulse transmission at the synapse.
(pp. 224 – 227)
R ESTING POTENTIAL
ACTION POTENTIAL
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ACTION POTENTIAL – G RAPH
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T RANSMISSION ACROSS A SYNAPSE
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QUESTIONS :
1.
2.
Match the description with the correct event.
______ More Na+ outside cell
More K+ inside cell
A.
Depolarization
______ Na+ ion gates open and Na+
rush into cell
B.
Hyperpolarization
______ K+ gates open & Na+ gates close;
K+ rush out of cell
C.
Refractory Period
______ More K+ moved out of cell than
necessary to reestablish charge
across membrane
D.
Repolarization
______ Na+ pumped out of cell & K+
pumped into cell
E.
Resting potential
How is the resting potential different from repolarization?
_____________________________________________________________
_____________________________________________________________
3.
Answer the following questions regarding the transmission of a nerve
impulse.
a.
What maintains the excess of Na+ outside the cell and an excess of
K+ inside the cell during the resting potential stage?
________________________________________________________
b.
The resting potential of a neuron (-70mV) indicates that the inside of
the cell is more negative than the outside. What two factors cause
this negative charge?
________________________________________________________
c.
What causes Na+ channels (gates) to open?
________________________________________________________
d.
What causes Na+ to rush into the neuron during depolarization?
________________________________________________________
Nervous System Activity #2 page 4
e.
What causes K+ to rush out of the neuron during repolarization?
________________________________________________________
f.
What causes the neuron to be hyperpolarized?
________________________________________________________
g.
What reestablishes the original distribution of K+ and Na+ during the
refractory period?
________________________________________________________
4.
Listed below is the distribution / movement of Na+ and K+ during the
transmission of a nerve impulse. Put the following in the correct order.
___1__ More Na+ outside the neuron; more K+ inside the neuron
______ Na+ gates open
______ Na+ gates close & K+ gates open
______ Na+ rushes into the neuron
______ K+ rushes out of the neuron
______ More K+ is outside the neuron; more Na+ is inside the neuron
______ Na+ is pumped out of the cell & K+ is pumped into the cell
5.
Define the following terms:
a.
Synapse:________________________________________________
________________________________________________________
b.
Presynaptic neuron:________________________________________
________________________________________________________
c.
Postsynaptic neuron:_______________________________________
________________________________________________________
Nervous System Activity #2 page 5
6.
Shown below is a diagram of a typical synapse. Color the following parts on
the diagram.
• Presynaptic neuron (A)
• Nerve impulse (D)
• Presynaptic membrane (E)
• Synaptic vesicle (F)
• Neurotransmitter (G)
• Neurotransmitter
fragment
1
(G )
Nervous System Activity #2 page 6
• Exocytosis (H)
• Synaptic cleft (I)
• Postsynaptic membrane (J)
• Receptor (G2)
• Endocytosis (K)
7.
Match the event below with the correct number from the diagram in question
#6.
______ Synaptic vesicles fuse with the presynaptic membrane releasing the
neurotransmitter into the synaptic cleft.
______ When the nerve impulse reaches the synaptic end bulb, Ca2 + gates in
the axon open allowing Ca2 + to enter the end bulb
______ The neurotransmitter diffuses across the synaptic cleft and bind to
the receptors on the postsynaptic membrane
______ The neurotransmitter is broken down; the fragments are then taken
into the end bulb by endocytosis
______ The neurotransmitter fragments are used to make new
neurotransmitter molecules
______ The flow of Ca2 + into the end bulb causes synaptic vesicles to
migrate toward the presynaptic membrane
8.
Match the structure with the correct letter from the diagram below.
______ Neurotransmitter
______ Postsynaptic membrane
______ Presynaptic membrane
______ Receptor site (protein)
______ Synaptic cleft
______ Synaptic end bulb
______ Synaptic vesicle
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