Sensory hair cells in ear. Coloured scanning electron micrograph (SEM) of hair cells in the cochlea, the inner ear's auditory sense organ. The crescent-shaped areas across centre are numerous stereocilia, and are located on top of supporting hair cells. Sound waves entering the inner ear displace the fluid that surrounds the stereocilia, causing them to bend. This triggers a response in the hair cells, which release neurotransmitter chemicals that generate nerve impulses. The nerve impulses travel to the brain along the auditory nerve. This process can transmit information about the loudness and pitch of a sound. Magnification: x2000 when printed 10cm wide.