What primarily causes deflection of vestibular hair cells in the semicircular canals?

What primarily causes deflection of vestibular hair cells in the semicircular canals?

• A. Ionic concentration changes
• B. Mechanical force
• C. Endolymph movement
• D. Cupula bending

Answer: (B)

Hair cells in the semicircular canals transduce mechanical stimulation. The deflection of their stereocilia is produced by a mechanical force applied to the hair bundles when the cupula is displaced by flowing endolymph during head rotation. The inertia of the endolymph causes it to lag behind the motion, bending the cupula and applying shear force to the hair cells. This mechanical force opens the directly gated ion channels and converts the motion into a neural signal. Ionic changes aren’t what deflect the hair cells, and while endolymph movement and cupula bending are part of the sequence, the immediate trigger is the mechanical force on the hair bundles.

Hair cells in the semicircular canals transduce mechanical stimulation. The deflection of their stereocilia is produced by a mechanical force applied to the hair bundles when the cupula is displaced by flowing endolymph during head rotation. The inertia of the endolymph causes it to lag behind the motion, bending the cupula and applying shear force to the hair cells. This mechanical force opens the directly gated ion channels and converts the motion into a neural signal. Ionic changes aren’t what deflect the hair cells, and while endolymph movement and cupula bending are part of the sequence, the immediate trigger is the mechanical force on the hair bundles.