Wikipedia offers an overall description of neurons. This site describes their physical appearance, the different parts of neurons, and what their functions are.

York University provides a good site on the physiology of nerve transmission. Embedded vocabulary help is available if you need it.

Introduction to neuron structure, function, and classification. Provides simple diagrams of neurons conducting an impulse and microscope images of nerve cells.

A frames page that gives the background to understand the way cells communicate (nerve cells). Each topic in the left frame triggers a tutorial on the right. Most have graphics or animated gifs to teach the material. Good background to...

A quick review to help students understand the function of different types of neurons in the human body.

Site provides the main function of the neurotransmitters serotonin, norepinephrine, acetylcholine, and glutamate.