Mechanoreceptors

A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. There are four main types: Pacinian corpuscles, Meissner's corpuscles, Merkel's discs, and the tympanic membrane.

Location
Mechanoreceptors are at the ends of neurons.

Cutaneous mechanoreceptors with small, accurate receptive fields are found in areas needing accurate taction (e.g. the fingertips). Mechanoreceptors with large, less accurate receptive fields are found in areas needing less precice taction (ie. the palm).

Functions
Cutaneous mechanoreceptors provide the senses of touch, pressure, vibration, proprioception and others. Mechanoreceptors can also be separated into categories based on their rates of adaptivity. 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 and the pulses will subside to a normal 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 normal firing rate are called ‘’tonic’’. Phasic mechanoreceptors are useful in sensing such things as texture, vibrations, etc; whereas tonic receptors are useful for temperature and proprioception among others.

In sensory transduction, the afferent neurons transmit the message through a synapse in the thalamus to the somatosensory cortex.