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 Wysłany: Wto 5:49, 19 Kwi 2011 Temat postu: Nike Air Griffey Max GD Mechanism of sensation |
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A mechanoreceptor is a sensory receptor that responds to mechanical pressure alternatively deformation. There are 4 chief types in the glabrous skin of humans: Pacinian corpuscles,[link widoczny dla zalogowanych], Meissner's corpuscles, Merkel's discs, and Ruffini corpuscles. There are too mechanoreceptors in the hairy skin, and the hair cells in the cochlea are the maximum perceptive mechanoreceptors in tranducing air pressure waves into sound.
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More recent work has amplified the character of the mechanoreceptors as response in fine motor control. Single action potentials from RAI and PC afferents are instantly linked to activation of related hand muscles,[1] whereas SAI activation does not trigger muscle play.
? The SAI type mechanoreceptor, with the Merkel compartment end-organ, underlies the perception of fashion and roughness on the skin.[2]
? The RAI type mechanoreceptor underlies the perception of flutter,[3] and slide aboard the skin.[4]
? Pacinian receptors underlie the perception of high frequency vibration.[5] SAII mechanoreceptors respond to skin stretch, but have not been closely linked to either proprioceptive or mechanoreceptive roles in perception.[6]
Types
There are 2 ways to categorize mechanoreceptors; by what kind of emotion they penetrate and by the rate of adaption.
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By sensation
Cutaneous mechanoreceptors provide the senses of touch, oppression, vibration, proprioception and others.
History
The person work stemmed from Vallbo and Johansson's percutaneous recordings from person volunteers in the late 1970s. Work in rhesus monkeys has found virtually identical mechanoreceptors with the exception of Ruffini corpuscles which are not found in the monkey.
? Slowly adapting type I mechanoreceptors have multiple Merkel corpuscle end-organs.
? Slowly accustoming type II mechanoreceptors have unattached Ruffini corpuscle end-organs.
? Rapidly adapting type I mechanoreceptors have multiple Meissner corpuscle end-organs.
? Rapidly adapting type II mechanoreceptors (ordinarily called Pacinian) have single Pacinian corpuscle end-organs.
By rate of adaption
Mechanoreceptors can also be separated into categories based on their rates of adaptivity. When a mechanoreceptor receives a stimulus it begins to launch thrusts or action potentials by one lifted frequency (the stronger the stimulus the higher the frequency). The cell, whatsoever,[link widoczny dla zalogowanych], ambition presently “adapt” to a constant or static stimulus and the pulses will subside to a customary rate. Receptors that adapt quickly (i.e. quickly return to a normal pulse rate) are referred to as ‘’phasic’’. Those receptors that are slow to return to their natural firing rate are phoned ‘’tonic’’. Phasic mechanoreceptors are serviceable in sensing such entities as texture, vibrations, etc; whereas tonic receptors are serviceable for temperature and proprioception in others.
Mechanism of sensation
Mechanoreceptors are primary neurons namely answer apt mechanical stimuli along firing operation potentials. Peripheral transduction is deemed to occur in the end-organs.
In sensory transduction, the afferent neurons transmit the information through a synapse in the dorsal column nuclei,[link widoczny dla zalogowanych], where dissimilar neuron sends the marking to the thalamus, where another neuron sends the signal to the somatosensory cortex.
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