Receptor potential, a type of graded potential, is the transmembrane potential difference of a sensory receptor.[1]
A receptor potential is often produced by sensory transduction. It is generally a depolarizing event resulting from inward current flow. The influx of current will often bring the membrane potential of the sensory receptor towards the threshold for triggering an action potential.
A receptor potential is a form of graded potential. An example of this is in a taste bud, where taste is converted into an electrical signal sent to the brain. When stimulated the taste bud triggers the release of neurotransmitter through exocytosis of synaptic vesicles from the presynaptic membrane. The neurotransmitter molecules diffuse across the synaptic cleft to the postsynaptic membrane.
Graded potentials vary in size. They arise from the summation of the individual actions of ligand-gated ion channel proteins, and decrease over time and space. They are distinct from voltage-gated sodium and potassium channels.[2]