1. Neurons

2. Parts of the Neuron
Cell Body – contains the nucleus and completes the metabolic activities needed to keep the cell alive.
Dendrites- short branched extensions of the cell attached to the cell body that take input from surrounding neurons.

3. Parts of the Neuron
Axon-long fiber that carries impulses away from the cell body.
Myelin sheath- insulator that speeds up impulses.

4. Parts of the Neuron
Nodes of Ranvier – highly conductive areas that jump-start the impulses
Axon Terminal- end of the axon where the impulse is converted into neurotransmitters

5. Parts of the Neuron Synapse – Area between neurons
Neurotransmitters – chemicals that are used to transmit the impulse from one cell to another.

6. How a Neuron Works: At Rest:
Cells pump sodium (Na+) out of the cell and potassium (K+) into the cell.
K+ leave the cell easily so the axon has a negative charge.

7. How a Neuron Works: Threshold
A neuron will only fire if a minimum level of stimulation is reached.
Too little stimulus = no firing
Above the level = firing

8. How a Neuron Works: When Fired-
The neuron pumps Na+ ions into the axon.
This makes a positive electrical charge which moves down the axon.
The cell returns to a resting state by pumping in K+.

9. How a Neuron Works: At the axon terminal-
The impulse triggers the release of neurotransmitters into the synapse.
The neurotransmitters attach to receptors on the next nerve cell.
This creates a stimulus that continues the cycle.