NERVE IMPULSE TRANSMISSIONOBJECTIVES:4. Explain how nerve impulses are generated and how they are conductedalong a nerve fiber (pp. 877 – 879)5. Describe the mechanism of nerve impulse transmission at the synapse.(pp. 877 – 879)

I. Neuron at restOutside is Positively charged due to Na+ ions.

Inside is negatively charged due to Nucleic Acids and Proteins

II. When the neuron is stimulated

• NA+ rushes in and creates the “Action Potential”• The inside is now positive(Action Potential).

Action Potential

AP

III. How does the neuron reset itself?1) Reset Charge:

K+ exits neuron

Action Potential

AP

III. How does the neuron reset itself?2) Reset Ions

K+ / Na+ pump resets the ions back to normal

Action Potential

What happens:

1. Impulse reaches end bulb2. Ca2+ channels/gates open and

Ca2+ enters3. Vesicles migrate and fuse with

membrane

4. Neurotransmitter released into Synapse

5. Neurotransmitter binds to receptors on adjacent neuron, causes it to depolarizes

Transmission Across a synapse Lab

1) Obtain a microscope and slide2) On your paper, draw a picture of

your slide on 400 power.3) Find the neuron and label the

following parts on your picture:– Axon– Presynaptic neuron– Vesicles– Postsynaptic muscle

Questions

1) What causes the vesicles in the neurons end bulb to release its contents?

2) What carries the nerve impulse across the synapse?3) What is another name for a nerve impulse?