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Cutaneous mechanoreceptors can also be separated into categories based on their rates of adaptation. When a mechanoreceptor receives a stimulus, it begins to fire impulses or action potentials at an elevated frequency (the stronger the stimulus, the higher the frequency). The cell, however, will soon "adapt" to a constant or static stimulus ...
Aδ fibers are characterized by thin axons and thin myelin sheaths, and are either D-hair receptors or nociceptive neurons. Aδ fibers conduct at a rate of up to 25 m/s. D-hair receptors have large receptive fields and very low mechanical thresholds, and have been shown to be the most sensitive of known cutaneous mechanoreceptors.
The initialization of sensation stems from the response of a specific receptor to a physical stimulus. The receptors which react to the stimulus and initiate the process of sensation are commonly characterized in four distinct categories: chemoreceptors, photoreceptors, mechanoreceptors, and thermoreceptors.
In physiology, a stimulus [1] is a change in a living thing's internal or external environment. This change can be detected by an organism or organ using sensitivity, and leads to a physiological reaction. [ 2 ]
External receptors that respond to stimuli from outside the body are called exteroreceptors. [4] Exteroreceptors include chemoreceptors such as olfactory receptors and taste receptors, photoreceptors (), thermoreceptors (temperature), nociceptors (), hair cells (hearing and balance), and a number of other different mechanoreceptors for touch and proprioception (stretch, distortion and stress).
Tactile perception is achieved through the response of mechanoreceptors (cutaneous receptors) in the skin that detect physical stimuli. The response from a mechanoreceptor detecting pressure can be experienced as a touch, discomfort, or pain. [23] Mechanoreceptors are situated in highly vascularized skin, and appear in both glabrous and hairy skin.
Stretch-activated ion channels are required for the initial formation of an action potential from a mechanical stimulus, for example by the mechanoreceptors in vibrissae (whiskers) of some animals such as rodents. Afferent nerve fibers responsible for sensory stimulus detection and feedback are especially sensitive to stimulation.
Typically the mechanical stimulus gets filtered in the conveying medium before reaching the site of mechanotransduction. [11] Cellular responses to mechanotransduction are variable and give rise to a variety of changes and sensations. Broader issues involved include molecular biomechanics.