Graded potentials are changes in membrane potential that vary according to the size of the stimulus, as opposed to being all-or-none. They include diverse potentials such as receptor potentials, electrotonic potentials, subthreshold membrane potential oscillations, slow-wave potential, pacemaker potentials, and synaptic potentials. The magnitude of a graded potential is determined by the strength of the stimulus. They arise from the summation of the individual actions of ligand-gated ion channel proteins, and decrease over time and space.[1] They do not typically involve voltage-gated sodium and potassium channels, but rather can be produced by neurotransmitters that are released at synapses which activate ligand-gated ion channels.[2] They occur at the postsynaptic dendrite in response to presynaptic neuron firing and release of neurotransmitter, or may occur in skeletal, smooth, or cardiac muscle in response to nerve input. These impulses are incremental and may be excitatory or inhibitory.
- ^ Mescher, Anthony L. (2013). Junqueira's Basic Histology Text & Atlas (13th ed.). McGraw Hill-Education. pp. 165–167. ISBN 978-0-07-180720-3.
- ^ Slish, Donald F. (2018). Pharmacology of Recreational Drugs The Neurology of How Drugs Work (1st ed.). United States of America: Cognella, Inc. p. 26. ISBN 978-1-5165-0441-1.