Final answer:
Otoliths are calcium carbonate-protein granules located on top of the otolithic membrane in the utricle and saccule of the inner ear, aiding in the sense of gravity and motion.
Step-by-step explanation:
The calcium carbonate-protein granules that enhance the sense of gravity and motion within the ear are known as otoliths. These otoliths are located on top of the otolithic membrane, which is a gelatinous substance in the utricle and saccule of the inner ear. The stereocilia of hair cells are embedded into this otolithic membrane and, with the help of otoliths, they respond to head movements by bending as the otolithic membrane moves.
When the head tilts, the otolithic membrane, made top-heavy by the otoliths, slides over the macula in the direction of gravity. As a result, the stereocilia bend, causing some hair cells to depolarize while others hyperpolarize. This activity is then interpreted by the brain to determine the exact position of the head.