Whether the merest whisper or an earth-trembling boom, the delicate apparatus deep within our ear vibrates helping us to perceive sound. Tiny bones rattle and create waves in a fluid-filled compartment, the cochlea. Undulation of the cochlea lining is sensed by thousands of hair cells whose ciliia (the cluster pictured is magnified 75000 times) jostle. This movement in turn morphs into a signal that nerves transmit to our brain, which acknowledges the ‘sound’. Mechanical wear by repeated exposure to loud noise, meningitis, or congenital disorders can cause deafness by damaging hair cells. Many thousands worldwide with profound impairment have had hearing restored by a cochlear implant. Hair cells are replaced with electrodes surgically positioned inside the cochlea and sound is received through a microphone fixed on the scalp. In the future stem cell therapy could supersede this form of treatment.
Written by Lindsey Goff
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences (the new name for the MRC Clinical Sciences Centre) the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.