This contains descriptions of various types of synapses

http://retina.anatomy.upenn.edu/~lance/eye/eye.html

You can find explanations of the structures of the eye here.

http://www.teleport.com/~veda/gallery.html

This shows a labeled diagram of the ear.

http://www.teleport.com

There are several text items explaining vestibular disorders: causes, diagnosis, and treatment.