Sunday, March 4, 2012
Transient changes in the membrane potential from its resting level produce electrical signals. Such changes are the most important way that nerve cells process and transmit information. These signals occur in two forms: graded potentials and action potentials. Graded potentials are important in signaling over short distances; thus, the changes in membrane potential are confined to a relatively small region of the plasma membrane. They are usually produced by some specific change in the cell's environment acting on a specialized region of the membrane. They are called "graded potentials" simply because the magnitude of the potential change can vary (is "graded"). Graded potentials are given various names related to the location of the potential or the function they perform, for instance, receptor potential, synaptic potential, and pacemaker potential.