Graded potentials - electrical characteristics and types

• A graded potential occurs when a gated channel is opened or closed, altering ion flow through the membrane. • Changes in ion and charge distributions cause voltage changes to the resting membrane potential. • The strength of the stimulus determines the number of gated channels affected and thus, the amount of ion flow. • The greater the stimulus the greater change in potential, hence the name graded potential. • Graded potentials can increase or decrease polarity: • An increase in polarity (more negative inside), caused by a decrease of lee ions inside, is called hyperpolarization. • A decrease in polarity (less negative inside), caused by an increase of Na+ ions inside, is called depolarization. • The role of graded potentials is to excite (depolarize) or inhibit (hyperpolarize) action potentials.

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