Final answer:
Change in sensory receptor membrane potential due to a stimulus is called a graded potential, which varies in size based on stimulus strength and can lead to an action potential if a threshold is reached.
Step-by-step explanation:
When a sensory receptor membrane depolarizes or hyperpolarizes, the change in membrane potential is called a graded potential. Graded potentials are local changes in the membrane potential that vary in size based on the strength of the stimulus. They can cause either depolarization or hyperpolarization. If a sensory stimulus such as temperature change or pressure is strong enough, the graded potential may reach a threshold that will trigger an action potential, which operates on an all-or-none principle. Unlike action potentials, graded potentials are not all-or-none; their amplitude can vary, reflecting the intensity of the stimulus that elicited them. These graded potentials, including receptor potentials and generator potentials, play a crucial role in the nervous system by initiating the electrical signals that can lead to an action potential.
In sensory systems, for instance, a light touch may generate a small receptor potential and may not lead to an action potential, whereas strong pressure can create a larger receptor potential that exceeds the threshold, thus triggering an action potential. The type of graded potential depends on where it occurs and what type of stimulus initiates it.