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