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Asked by chocoholiclea to Amy, Drew on 24 Jun 2011. This question was also asked by jackietang.
Keywords: dizzy, spin
Its to do with the bones, nerves and fluid in our ears – believe it or not!!
Rolling down a hill or spinning around causes dizziness because hair-like sensory nerve cells in our ears send wrong messages to our brain.
The vestibular system is found in the upper part of our inner ear and this detects the motion of our bodies – when we spin we feel dizzy and lightheaded due to the vestibular system’s nerve reactions to these unusual motions.
So how does the vestibular system work? well it senses motion through three semicircular canals in your ear that are at right angles to one another. These canals have hair-like sensory nerve cells and contain a fluid called endolymph.
When we spin, our brain receives mixed messages. The endolymph slowly begins to move in the same direction we are spinning. As time goes by, the endolymph catches up to the rate of speed we are spinning and no longer stimulates the hair-like nerve cells. This causes our brain to quickly adapt to the nerve signals. However, when we stop spinning, the endolymph continues to move and stimulates hair cells in the opposite direction….aaaaghh brain confusion!!!
These hair cells send wrong messages to the brain making it think that the head is still spinning although it actually has stopped. As a result of this inaccurate signal, we experience dizziness. Eventually, the endolymph stops moving and no more signals are sent to the brain. The brain interprets that the spinning motion has ceased and the dizziness disappears.
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