There are three types of neurons:

The motor neuron which is located in the motor cortex, brainstem or spinal cord.  Its axon connects directly to muscle fibers and is involved with organs, muscles, and glands.

The interneuron also is known as the connector neuron because it connects the motor and sensory neurons within the central nervous system by enabling communication circuits.  They have also been found to function in reflexes.The sensory neuron receives environment information and transmits this information into nerve impulses through synapses with other neurons to the central nervous system.There are four stages of action potential.  Resting (polarized membrane), depolarization, repolarization, and flow of depolarization.

During resting, there are positive and negative ions.  If there are more positive ions outside then the inside of the axon would be negative.  During depolarization, negative ions travel outside of the axon and become positive.  This creates off balanced ions.  Repolarization allows the positive ions from the outside to come into the axon and become negative.  This creates balance again. Finally, the flow of depolarization causes the action potential to continuously move down the axon to continue.

A synapse is a junction between two neurons and is the way they communicate with one another.  Here is what a labeled structure of a synapse looks like:

The action potential triggers the presynaptic neuron and becomes neurotransmitters (chemical substance).  They then bind to the receptors on the postsynaptic cell and make it more or less likely to trigger an action potential.  This is a chemical reaction that takes place.

There are six main neurotransmitters.  Acetylcholine which effects muscle contractions and memory/learning, serotonin which affects mood, sleep patterns and appetite, dopamine which affects mood, motivation and gives you a sense of reward, glutamine which affects memory and learning, GABA which increases relaxation, and endorphins help with pain relief and cause sleepiness.  GABA and glutamate are the only inhibitory neurotransmitters which mean they can prevent a process, reaction or function.