The dendrites, or "tentacles," of a neuron pick up an electrical nerve impulse and conduct it toward the soma, or cell body. The nerve impulse travels through the soma and is then conducted down a threadlike fiber called the axon. At the end of the axon, the impulse travels over a gap called a synapse to reach the dendrites of the next cell.
When a neuron is at rest, it is in a state of polarization. There is an excess of sodium (Na+) ions outside of the cell membrane that create a positive charge. Similarly, there is an excess of potassium (K+) ions inside the cell along with negatively charged molecules that produce a negative charge inside the cell membrane.
When a neuron is stimulated, either from direct sensory input or another neuron, ion channels in the cell membrane open, and sodium ions rush in. The inside of the cell becomes positively charged, the cell depolarizes and an action potential is created that transmits the stimulus down the axon.
At the end of the axon, the nerve impulse reaches the synapse. Neurotransmitters are then released to carry the nerve impulse across the synapse to the dendrites of the next neuron.