It's the sodium ion.
When a neural impulse is fired in both neurons, it is always cause by an excited electron in one neuron moving to the other neuron to destabilize the balance of ions trying to keep them at equilibrium. This action either depolarizes or hyper-polarizes the membrane. If it does, then sodium ions--the key deficient ones--can flow into that region of low charge and maintain that state of low charge, keeping the cell membrane stable.
In both processes sister chromatids are pulled apart, as can be seen by the image at anaphase.
Well, on average 2/3 of a persons weight is water.
True because Sigmund Freud (1890-1930) developed these collection of theories
