mechanoreceptor

Mechanoreceptors are sensory receptors that detect mechanical forces and convert them into electrical signals in the nervous system. They respond to stimuli such as touch, pressure, vibration, skin stretch, and body movement, contributing to tactile perception, proprioception, and balance. Mechanoreception occurs in specialized nerve endings and sensory epithelia, with signals transmitted by peripheral nerves to the spinal cord and brain.

Cutaneous mechanoreceptors in the skin include both encapsulated and non-encapsulated endings. Rapidly adapting receptors such as Meissner corpuscles detect low-frequency vibration and light touch, while Pacinian corpuscles sense high-frequency vibration. Slowly adapting receptors like Merkel cells provide fine spatial discrimination, and Ruffini endings respond to sustained pressure and skin stretch. Hair follicle receptors sense movement of hair. Deeper mechanoreceptors include muscle spindle endings and Golgi tendon organs, which monitor muscle length and force, and joint capsule receptors that contribute to proprioception.

In the inner ear, hair cells act as mechanoreceptors for hearing and balance. Deflection of their hair bundles opens mechanosensitive ion channels, generating receptor potentials that trigger neurotransmitter release and signal transmission to the brain.

Transduction typically involves mechanically gated ion channels that convert physical deformation into electrical signals. Some channels, such as those in the Piezo family, are central to many mammalian mechanoreceptors. Receptor potentials may summate to elicit action potentials in the associated sensory neurons. Adaptation rates vary: some receptors are rapidly adapting, signaling dynamic changes, while others are slowly adapting, signaling sustained stimuli.

Clinical relevance includes the assessment of touch and proprioceptive function, which can be impaired in peripheral neuropathies or after nerve injury.