What makes Human a Conductor Conductors, are those which have free electrons... and because of this have same electric potential all over. But considering our body, which has many electrical voltage, current signals passing by in neurons, skeletal muscles(also the ones in heart creating dipole), etc, how are we being conductors... that is I meant, where are free charge originated in us.. Are just metal ions responsible for this ?
 A: Conduction is the transport of charge, and it doesn't matter what the charge carriers are. In metals the charge carriers are, as you say, the conduction electrons. However in electrolyte solutions like saline the conductors are hydrated ions like $\textrm{Na}^+$ and $\textrm{Cl}^-\;.$
As far as electricity is concerned our bodies are basically just dilute electrolytes, so the (rather low) conductivity of the human body is due to transport of ions.
You mention conduction in nerves. This is a bit of a special case because the main action of nerves is not to conduct electricity but to propagate changes in electrical potentials. Describing the mechanism by which nerves work would be off topic here but is easily Googled.
A: Google it and you will get great answers for example :

PURE WATER DOES NOT CONDUCT ELECTRICITY. It's all the salts and impurities in it that cause it to carry current. Skin is actually a very good insulator as well so, relative to metal, humans aren't very good conductors. However, it is things such as the ionized water and whatnot that make up our body that do cause us to conduct.
Actually the body is not too good. That is the reason that you get a shock as your body is a resistance not in fact a pure condutor. If you get an ordinary electricity multimeter and test your restance from one hand to another you will see that it is in fact quite high. That is reason that you cannot feel 12volt. Now when the body surface is moist then you get a greater contact area and the body resistance will drop hence putting a battery across your toungue induces a tingle.
Humans are actually horrible conductors. The typical resistance of any human is about 6 Meg Ohms. Copper is only a few ohms (depending on the length). But we do conduct because we are 70% water, (though pure water wont conduct electricity either.)

Source : yahoo answers
