Keeping You Right Ways Up

‘Hair cells in the utricle’ by David Furness. CC BY-NC

Some say the five senses are smell, hearing, sight, touch, and taste, but those are just the major ones. Take orientation, for example. Tip your head forward or backward and there’s no mistaking it, even with your eyes closed. That’s because these organ pipe-shaped cells sense when your head isn’t level and pass the message onto your brain.

Located in the upper half of your inner ear (which goes by the name utricle), these hair cells (pictured in blueish-purple) respond to the pull of gravity — just not directly. They’re too small and light. Rather, this gravity-sensing organ relies on little crystals called otoliths, which means ear rocks in Greek. Made from the main ingredient in pearls and sea shells, these grains weigh down a gel surrounding the hair cells. When you tilt, they tilt, bending the gel and bringing along the hair cells, who then inform your brain that you’re off-kilter.

About the Author

Charlie Wood

Charlie Wood is a science writer with a bachelor’s degree in physics from Brown University and a master’s degree in science journalism from New York University. In previous lives he taught physics in Mozambique and English in Japan, but these days he freelances from his home in New York.