Intro | Free Nerve Endings | Meissner's Corpuscle | Merkel's Disks | Pacinian Corpuscle | Ruffini Corpuscles | Subcutaneus Fat | Sweat Gland
Part 1: Image-Mapped Tutorial
Part 2: Matching Self-Test
Part 3: Multiple-Choice Self-Test
The Pacinian Corpuscle is the largest receptor type found in the skin (0.5 x 1.0 mm or visible to the naked eye). It is a globular structure made of multiple layers (up to 70) like an onion and is found deep within the subcutaneous layer of both glabrous and hairy skin, the external genitalia, mammary glands, and internal organs. The receptive field of Pacinian corpuscles is large. This receptor is very quick to adapt to displacement of the skin; making it specialized for the reception of high frequency touch or vibration. When the corpuscle is moved relative to the axon, the membrane depolarizes. Ion channels are opened by the mechanical displacement of long carbohydrate chains that are anchored to protein filaments that in turn attach to the membrane beneath the channels. The layered structure of the corpuscle renders it briefly responsive to both the bending and release of the organ. Thus, the Pacinian corpuscle does not detect steady pressure.
| Advanced |
Psychophysical studies of pain receptors (Darian-Smith, 1984) indicate that the transient response of Pacinian corpuscles to indentation of the skin shows a peak in sensitivity at approximately 300 Hertz with a displacement of less than 1 micrometer. The discharge of action potentials is phase-locked with the stimulus events. These corpuscles lose sensitivity at low stimulus frequencies.
A recent study directly compared the contribution of high frequency vibration receptors (Pacinian corpuscles) with low frequency vibration receptors (Meissner's corpuscles) to the process of localizing the position of such stimuli (Sherrick, Cholewiak & Collins, 1990). Both receptor density and the gradient of receptors across the skin contributed to the localization of vibratory stimuli. Due to the larger receptive fields of Pacinian corpuscles, their contribution to localization is less efficient than that found for Meissner's corpuscles.
| References |
Darian-Smith, I (Ed.). (1984). The handbook of physiology: sensory processes (Volume III, Parts 1 and 2). The American Physiological Society.
Sherrick, C.E., Cholewiak, R.W., Collins, A.A. (1990). The localization of low- and high-frequency vibrotactile stimuli. Journal of the Acoustic Society of America, 88(1), 169-179.