Final answer:
The sequence from sensory stimulus to a change in membrane potential involves receptor potentials, graded potentials and may lead to an action potential if the depolarization reaches a threshold.
Step-by-step explanation:
The sequence of events starting with a sensory stimulus and ending with a change in membrane potential is known as the formation of a receptor potential. This process begins when a sensory signal, such as pressure or temperature, is detected by receptors like mechanoreceptors or thermoreceptors.
Then, ion channels in the neuron's membrane open, leading to a change in membrane potential. If this change, called a graded potential, is significant enough to reach a threshold, an action potential is triggered, which is the electrical impulse that travels along the neuron.
Graded potentials are local and their magnitude varies with the strength of the stimulus. The action potential, on the other hand, is an all-or-nothing event that occurs when the membrane depolarizes to a certain level. It is characterized by a rapid influx of sodium ions followed by an efflux of potassium ions, which propagates the electrical signal along the axon to the next neuron or to an effector such as a muscle or gland.