some help please

[özge]

http://img347.imageshack.us/img347/3082/adsz5hb.th.jpg (http://img347.imageshack.us/my.php?image=adsz5hb.jpg)
this is a figure from a neuron
can anyone explain why not sodium ions cross the cell membrane?

[BerryBoy]

http://www.bris.ac.uk/synaptic/public/basics_ch1_2.html
This is a good site at explaining how neurons work; complete with animations.

Sam.

[gamze]

perhaps you can search Na/K ATPase