Describe the physiological mechanism by which physical pressure applied to a Pacinian corpuscle generates a depolarisation in the membrane of its sensory neurone.

An investigation was carried out to record changes in the membrane potential of a sensory neurone when two different stimulus intensities (Stimulus A and Stimulus B) were applied to a Pacinian corpuscle. The results are shown in the graph below.

Draw on this

With reference to the graph, explain how the recordings illustrate the all-or-nothing principle of nerve impulse propagation.

Between 1.0 ms and 4.5 ms, even a massive, supra-threshold stimulus cannot initiate a second action potential. State the term given to this period of time.