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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).
The inter-spike intervals during sustained firing are irregular, in contrast to the highly regular pattern of inter-spike intervals obtained from slowly adapting type II mechanoreceptors. [citation needed] They fire fastest, when small points indent the skin, and fire at a low rate on slow curves or flat surfaces. Convexities reduce their rate ...
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.
The receptive field, or sensory space, is a delimited medium where some physiological stimuli can evoke a sensory neuronal response in specific organisms. [1]Complexity of the receptive field ranges from the unidimensional chemical structure of odorants to the multidimensional spacetime of human visual field, through the bidimensional skin surface, being a receptive field for touch perception.