The neurons are the electrical wiring of the body. All thoughts, commands to muscles, and sensory inputs happen through this system. The spinal cord is a lot like the main wiring harness to your car that carries information about speed, gas level, temperature, etc. That wiring can also send commands, turn on the headlights, honk the horn, turn on the windshield wiper motors.
Neurons receive input at one end from a branch structure, called Dendrites. They receive the signal and can pass it along through their axon to a dendrite at the tail end of their axon. Axons, similar to a wire, can run quite a distance, up to about three feet. The electrical signal runs along them and can be transmitted, much like a game of telephone from neuron to neuron. While neurons can take input from many other neurons from their dendrites, they only transmit through one axon.
At the end of the axon is a bulb, or ball. That synaptic knob and the Dendrite do not actually connect, the distance between them is called the synaptic gap. The electrical impulse is actually conducted by chemical neurotransmitters. These transmitters get released by the axon when the pulse hits them. The pulse opens up the bulbs and the transmitters go to the receptors on the next neuron. These transmitters can either excite or inhibit the receptors of the next neuron in the chain.
