Neuron Depolarization

There are billions of neurons in the human body which work together and govern our thoughts, sensations and movement. Neurons, or any cell for that matter, have the ability to hold a charge in their membrane. The charge itself is caused by the passage of positively and negatively charged ions through ion channels and pumps in the membrane itself. In the human body the main positive charged ions you will find are sodium (Na), potassium (K), and calcium (Ca). Largely chloride (Cl) will be the only negatively charged ion effecting neurons.

Depolarization and the flow of these ions is governed by both the concentration and electrical gradients. At rest, the average neuron will be at about -70mV. This charge is governed by the equilibrium potential of the Na+ and K+ ions flowing between the membrane and the exterior of the cell. The concentration of K+ will be greatest inside the cell and low outside he cell. In contrast, Na+ will have a high concentration outside the cell and a low concentration inside the cell. Therefore when say, a K+ channel opens, large amounts of K+ will leave the cell, pushing its electrical potential more negative and hyperpolarize it. When an Na+ channel opens, large amounts of Na+ will rush into the cell, pushing its electrical potential to be more positive and depolarizing it.