Question

How are electric impulses generated in our body?

Answer 1

you mean like, in nerve cells?

it is the same principle as in a galvanic cell (setup like this one: http://en.wikipedia.org/wiki/Galvanic_cell ).

now, the "porous disk" is the cell membrane. ions can't pass, except through special channels that open and close under certain conditions. now, you put in certain ions on both sides of the membrane:

- potassium on the inside
- sodium on the outside



now, potassium will want to diffuse to the outside, because of the concentration difference. but if it does that, the membrane will be charged and doesn't want that. a force will be generated to push the potassium back into the cell. if both forces are leveled out (Nernst equation!), this is your resting potential, around -70 mV.

now if, by chance, this membrane potential is changed through an opening of calcium ion channels, the membrane potential will change rapidly! this will cause voltage-dependent sodium channels to open. this will again cause the membrane potential in their "part" of the membrane to change, additional voltage-dependent sodium channel will open and so forth.

thus, electric impulses are generated. by the influx of charged particles through a charged an electrically unstable membrane.