Here are a couple of web sites that may be of some interest for you to look at:
http://gsbs.utmb.edu/microbook/ch033.htm
http://www.iol.ie/~alank/CROHNS/PRIMER/human.htm
Adrian.
Adrian R. Tappin
"Home of the Rainbowfish"
http://www.ecn.net.au/~atappin/home.htm