The nervous system is a very complex organ system. These types of graded potentials occurs in the neurons and they are as a result of the activation of ligand-gated channels. Resting Membrane Potential Easy And Simple Explanation Biology Notes Dental Hygiene School Class Notes The membrane potentials that are less than the depolarizing potentials are called graded potentials. . Both of these ions have higher concentrations outside the. Hyperpolarizing are called INHIBITORY POSTSYNAPTIC POTENTIALS IPSPs the ionic basis of postsynaptic potentials is considered under neurotransmission. Both of these ions have higher concentrations outside the cell than inside. A depolarizing graded potential at a synapse is called an excitatory PSP and a hyperpolarizing graded potential at a synapse is called an inhibitory PSP. Describe the changes that occur to the membrane that result in the action potential. Graded Potential- The graded Po