Mechanoreceptors


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Mechanoreceptors

Sensory receptors that provide the organism with information about such mechanical changes in the environment as movement, tension, and pressure. In higher animals receptors are actually the only means by which information of the surroundings is gained and by which reactions to environmental changes are started. See Sensation

Mechanoreceptors are excited by mechanical disturbances of their surroundings through deformation of their structure, through pressure or tension, or through a combination of these. In general, little energy is required for mechanical stimuli to cause a detectable excitation in mechanoreceptors.

From a physical point of view, mechanoreceptors are energy transducers; they convert mechanical into electrical energy, which in turn triggers the nerve impulse. Deformation leads to a sequence of events which may be summarized by the following scheme: The generator current is the earliest detectable sign of excitation. The most salient characteristic of the generator current is its graded nature; its amplitude increases continuously, without visible steps, if the stimulus strength is progressively increased. When the generator current reaches a certain critical amplitude, an all-or-nothing potential is discharged in the sense organ which may then propagate as an all-or-nothing nerve impulse along the afferent axon of the receptor. See Nervous system (invertebrate), Nervous system (vertebrate)

Mechanoreceptors

 

sensory nerve endings that receive various mechanical stimuli from the external environment or viscera.

Some mechanoreceptors, called tactile receptors and concentrated in the outer integuments of animals and man, are sensitive to touch. Baroreceptors (pressoreceptors, volumoreceptors), found in the walls of the blood vessels, the heart, and hollow smooth-muscled organs, react to distension associated with elevated blood pressure or accumulated gases in the stomach or intestine. Proprioceptors are mechanoreceptors found in the musculoarticular apparatus that react analogously to the contraction or relaxation of the skeletal muscles. The mechanoreceptors of the vestibular apparatus, called vestibuloreceptors, respond with neural impulses to acceleration, vibration, or inclination of the body or head. The specific characteristics of a stimulus are coded in the mechanoreceptors by the frequency and rhythm of their impulses.

References in periodicals archive ?
Several investigators already showed increased muscle activity following joint afferent fiber or mechanoreceptor stimulation and activation of gamma motor neurons (42,43).
Several factors could possibly affect muscle activation after passive stretching, such as neuromuscular feedback responses [Golgi tendon reflex, mechanoreceptor (type III afferent)] and mechanical changes [muscle stiffness, force-length relationship] (Avela et al., 2004; Behm et al., 2001; 2004; Behm and Chaouachi, 2011; Behm and Kibele, 2007; Pacheco et al., 2011; Rubini et al., 2007; Shrier, 2004; Thacker et al., 2004).
(15.) Gladwell V, Coote J, Heart rate at the onset of muscle contraction and during passive muscle stretch in humans: a role for mechanoreceptors. J Physiol.
The orthoses may enhance ligament mechanoreceptor function and cause the stimulation of a greater number of peroneal motoneurons and then increase balance., Orthoses can improve balance, prevent injury and its reoccurrence.
(15,16) A number of mechanisms are proposed for the increase in motor neuron excitability or the removal of motor neuron inhibition with spinal manipulation, including altered excitability of mechanoreceptors in paraspinous tissue, altered discharge from muscle spindles or Golgi tendon organs, increased pain tolerance, increased opiate release, and alteration in sympathetic nervous system activity.
It has been suggested that KT has more influence on skin and muscle mechanoreceptors and less on joint receptors (Chang et al., 2010).
The decrease in partial pressure of oxygen at altitudes reduces the brain supply of [O.sub.2] and results in increased blood flow in the organ up to 26% [6] which consequently swells the brain leading to the traction of the meninge and headache due to local traction-irritable mechanoreceptors [7,8].
As for the former, studies with animal models suggest that stimulation of mechanoreceptors in the stomach would lead to increased sympathetic activity (16,17).
(14) Connective tissue insufficiency is a term to describe the loss of tissue strength related to degenerative change, which results in loading and stimulation of relatively fixed-length pain mechanoreceptors. (15)
The function of chemo- and mechanoreceptors in lobster (Homarus americanus) feeding behaviour.
Data from animal studies of the biomechanical properties of the lateral ankle ligaments and their relationship to the distribution of mechanoreceptors in the ligaments suggests that mechanoreceptors in the lateral ligament may contribute to the stability of the joint by regulation of position and movement (Takebayashi et al 1997).
It also increases tissue perfusion and stimulates mechanoreceptors. When we talk about the effect of deep friction massage in tendinitis around shoulder, it stimulates circulation, which overcomes the congestion within the tendon, reduces/ prevents adhesion formation.