Neurons, Nervous System, and Signal Transmission Practice Test 2026 - Free Practice Questions and Study Guide

The main idea tested is how sound becomes a neural signal. The cochlea is the hearing portion of the inner ear. It takes mechanical vibrations that travel through the middle ear and converts them into electrical signals. Inside, the organ of Corti sits on the basilar membrane and contains hair cells. When the basilar membrane moves in response to sound, the hair cells’ stereocilia bend, opening ion channels and creating receptor potentials that release neurotransmitters onto auditory nerve fibers. This sends the signal to the brain for interpretation of pitch and loudness. The cochlea also maps frequencies along its length, with high frequencies detected at the base and low frequencies at the apex. In contrast, the external auditory canal and pinna mainly gather and funnel sound, while the semicircular canals manage balance. So the cochlea is primarily involved in hearing.