Pacinian corpuscles (PCs) are rapidly adapting mechanoreceptors found in the skin and some internal organs. These specialized structures play a central role in sensing vibrations and changes in deep pressure. Understanding their electrical response mechanism is fundamental in neurophysiology.

The Electrical Response of Pacinian Corpuscles

Pacinian corpuscles convert mechanical stimuli into electrical signals through the following steps:

• Small pressure application generates a local, non-propagated depolarizing potential in the nerve ending, called the receptor potential (or generator potential).alevelbiologyyoutube

• Increasing pressure results in an increased magnitude of this receptor potential; this is a graded, not all-or-none, response.alevelbiology

• Critical receptor potential: If the stimulus is strong enough to depolarize the nerve terminal beyond a threshold, an action potential is generated at the first node of Ranvier. This action potential is all-or-none, but the receptor potential that precedes it is not.youtube

• The receptor potential magnitude tracks stimulus strength; thus, receptor potentials are graded, not all-or-none.wikipedia+1

• The receptor potential itself is not propagated along the nerve and is distinct from the action potential, which does propagate.youtubealevelbiology

Evaluating the Statements

Let’s analyze the statements for correctness:

• A. A non-propagated depolarizing potential or receptor potential is elicited when small magnitude of pressure is applied to PC.
  This is correct; weak stimuli cause localized depolarization in the PC.alevelbiology

• B. The magnitude of receptor potential is increased as the pressure to PC is increased.
  This is correct; receptor potential amplitude is proportional to stimulus intensity.alevelbiology

• C. An action potential is generated when receptor potential attains a critical value.
  This is correct; action potential occurs if receptor potential exceeds threshold.youtube

• D. The receptor potential shows all-or-none response.
  This is incorrect; receptor potential is graded, not all-or-none.wikipedia+1

• E. The receptor potential is not a graded potential.
  This is incorrect; receptor potentials are graded by definition.wikipedia+1

Correct Option: INCORRECT Statements

The pair that contains both incorrect statements:

(4) D and E

• D incorrectly describes receptor potential as all-or-none.

• E incorrectly describes receptor potential as non-graded.

Conclusion

Understanding Pacinian corpuscle physiology reveals that receptor potentials are localized, graded, and increase with stimulus intensity, but only action potentials are all-or-none. Clear distinction between graded receptor potentials and all-or-none action potentials is central to grasping sensory adaptation and transmission in these rapidly adapting mechanoreceptors.