THE NERVOUS SYSTEM
How do neurons communicate?
THE ROAD TO CEPHALIZATION…
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1.
Which letter
represents the
dendrite of the
sensory neuron?
2.
What type of cell is found only in the central
nervous system?
What structure conducts nerve impulses from
the spinal cord to the gall bladder?
3.
TRY THIS!
1.
Which letter
represents the
dendrite of the
sensory neuron?
W
2.
What type of cell is found only in the central
nervous system? Interneuron
What structure conducts nerve impulses from
the spinal cord to the gall bladder?
Motor Neuron
3.
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What event occurs during repolarization?
A. the sodium gates open
B. the potassium gates open
C. the net movement of sodium ions into the axon
D. the net movement of potassium ions into the
axon
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What event occurs during repolarization?
A. the sodium gates open
B. the potassium gates open
C. the net movement of sodium ions into the axon
D. the net movement of potassium ions into the
axon
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Which of the following occurs between time X and
time Y?
A. repolarization
B. depolarization
C. resting potential
D. refractory period
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Which of the following occurs between time X and
time Y?
A. repolarization
B. depolarization
C. resting potential
D. refractory period
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What event occurs during depolarization?
A. the sodium gates close
B. the potassium gates open
C. the net movement of sodium ions into the axon
D. the net movement of potassium ions into the axon
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What event occurs during depolarization?
A. the sodium gates close
B. the potassium gates open
C. the net movement of sodium ions into the axon
D. the net movement of potassium ions into the axon
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
Tell the story of how information travels from
your spinal cord to the muscles of your arm to
make them move. Include the following terms:
Resting potential
 Action potential

Depolarization
 Repolarization

Refractory Period
 Propagation

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
Compare resting potential and action potential
Resting Potential
Action Potential
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
Compare resting potential and action potential
Resting Potential
Action Potential
- Active transport with
ATP
- Passive transport with
no ATP
- Carrier protein
sodium/potassium pump
- Gated channel
proteins: sodium gate
and potassium gate
- Maintains
concentration gradients
- Ions flow down
concentration gradients
-65mV
-depolarization: -40mV
(threshold) to +40mV;
repolarization: +40mV
to -65mV
PROPAGATION OF THE NERVE
IMPULSE
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
Where in the myelinated axon would an action
potential actually occur?
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
Where in the myelinated axon would an action
potential actually occur?
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
How does a neuron respond to a strong stimulus?
A. It produces a larger action potential
B. It causes more ions to move across the
neuron membrane
C. It causes more action potentials in a given
period of time
D. It causes action potentials to be conducted at
a faster speed
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
How does a neuron respond to a strong stimulus?
A. It produces a larger action potential
B. It causes more ions to move across the
neuron membrane
C. It causes more action potentials in a
given period of time
D. It causes action potentials to be conducted at
a faster speed
TRANSMISSION ACROSS THE
SYNAPSE

Animation
TRANSMISSION ACROSS THE
SYNAPSE

Nerve impulse reaches the axon bulb

Ca2+ ions move into the axon bulb.


Ca2+ ions interact with contractile proteins
and pull the vesicles containing
neurotransmitters to the surface of the
presynaptic membrane.
The vesicles merge with the presynaptic
membrane and release neurotransmitters
into the synaptic cleft by exocytosis.
TRANSMISSION ACROSS THE
SYNAPSE




The neurotransmitters diffuse across the cleft.
The neurotransmitters bind with specific
receptors on the postsynaptic membrane.
Depolarization occurs on the postsynaptic
membrane if threshold is reached.
The neurotransmitter is destroyed by an
enzyme (ex. acetylcholinesterase) or reabsorbed
back into the presynaptic membrane.
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
Which of the following describes the role of
calcium ions during synaptic transmission?
A. They cause Y to become inactivated.
B. They act as carriers to move Y toward Z.
C. They cause Y to undergo endocytosis at W.
D. They initiate the process that results in X
moving toward W.
TRY THIS!

Which of the following describes the role of
calcium ions during synaptic transmission?
A. They cause Y to become inactivated.
B. They act as carriers to move Y toward Z.
C. They cause Y to undergo endocytosis at W.
D. They initiate the process that results in X
moving toward W.
TRY THIS!

Tell the story of how information travels from
your spinal cord to the muscles of your arm to
make them move. Include the following
processes:
Resting potential
 Action potential

Depolarization
 Repolarization

Refractory Period
 Propagation
 Transmission
across the Synapse
