Describe Equilibrium Receptors and Their Physiology

Equilibrium

• awareness and monitoring of head position

• vestibular apparatus: utricle, saccule, semicircular ducts

  • utricle and saccule = static equilibrium and linear acceleration

  • semicircular ducts = angular acceleration

Static equilibrium and linear acceleration

• macula = receptor for static and linear

  • in utricle and saccule of vestibule

  • layer of hair cells and supporting cells

    • stereocilia and one kinocilium projecting into otolithic membrane (covered with otoliths - calcium carbonate crystals)

• head tilts = shifts otolithic membrane, bends stereocilia

  • bending toward kinocilium = depolarization = increase NT release = increase impulse frequency on CN VIII

  • opposite reaction bending away

Angluar acceleration

• ampulla: base of semicircular canal

  • contains crista ampullaris with hair cells and support cells

    • stereocilia and kinocilia hair cells in gelatinous cupula

• head rotates = endolymph pushes against cupula = cupula bends sterocilia changing hair cell voltage

  • bent toward kinocilium = depolization

  • bent away = hyperpolarize

    • NT release from hair cell changes

    • firing rate changes on vestibular branch of CN VIII

Woohoo

All done