Final answer:
The receptors that respond to head tilt due to gravity are found in the vestibular system in the inner ear, where tiny crystals cause hair cells to bend and send signals to the brain. Displacement of these crystals, as occurs in BPPV, can cause dizziness by triggering inappropriate stimulation of hair cells.
Step-by-step explanation:
The receptors that respond to head tilt via gravity-induced deformation are located in the vestibular system of the inner ear. The sensation of balance and spatial orientation is primarily facilitated by gravity's effect on tiny crystals, known as otoconia, within the utricle and saccule of the vestibular labyrinth. These crystals overlay the gelatinous layer that contains the hair cells' stereocilia. When the head tilts, gravity pulls on these crystals, causing the underlying hair cells to bend. The bending of the hair cells transduces the mechanical energy into neuro-electrical signals that are sent to the brain for processing, allowing us to perceive head position and maintain balance.
In Benign Paroxysmal Positional Vertigo (BPPV), some of these crystals can migrate into the semicircular canals, which are not meant to respond to gravity. This causes episodes of dizziness because the hair cells in the semicircular canals become inappropriately stimulated by the gravitational pull on the dislodged crystals, triggering false signals of head movement.