THE NERVOUS SYSTEM

How do neurons communicate?

T HE ROAD TO C EPHALIZATION …

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1.

Which letter represents the dendrite of the sensory neuron?

2.

3.

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?

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1.

Which letter represents the dendrite of the sensory neuron?

W

2.

3.

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

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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

- Active transport with ATP - Carrier protein sodium/potassium pump - Maintains concentration gradients -65mV

Action Potential

- Passive transport with no ATP - Gated channel proteins: sodium gate and potassium gate - Ions flow down concentration gradients -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.

C.

D.

It causes more ions to move across the neuron membrane It causes more action potentials in a given period of time 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.

C.

D.

It causes more ions to move across the neuron membrane

It causes more action potentials in a given period of time

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 

Ca 2+

ions move into the axon bulb.



Ca 2+

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.

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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.

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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 processes:    Resting potential Action potential   Depolarization Repolarization Refractory Period   Propagation Transmission across the Synapse