Theoretically, a recognized member of the modern state system possessing formal sovereignty and occupied by a people who see themselves as a single, united nation. Most nations and states aspire to parlance, nation-state is used as a synonym for country or state.
In biology, depolarization is a decrease in the absolute value of a cell's membrane potential. Thus, changes in membrane voltage in which the membrane potential becomes less positive or less negative are both depolarizations.
On the left is the action potential of an autorhythmic cell; on the right, the action potential of a contractile cell. Autorhythmic cells exhibit PACEMAKER POTENTIALS. Depolarization is due to the inward diffusion of calcium (not sodium as in nerve cell membranes). Depolarization begins when: 1  the slow calcium channels open (4), 2  then concludes (quickly) when the fast calcium channels open (0).