How is it someone becomes dizzy after spinning around in a circle…?
What exactly happens to that persons sense of balance and what are the effects on the human brain at the time?
Why does it happen? And what keeps a human’s sense of balance in the first place?
I won’t answer all your questions.
We have structures deep within our ears that are filled with fluid. These are called the semicircular canals (and utricle and saccule). The three semicircular canals are at right angles to one and other.
Because of inertia, the fluid in the canals lags behind the head when we turn or move. So, if our head moves to the left, the fluid lags behind as if it moves to the right. Tiny structures in the lining of the canals sense the relative movements of the fluid within and they send signals to the deeper part of the brain that enable us to figure out which way we’re moving. Of course, this is all done near instantaneously and unconsciously.
By having the three semicircular canals at right angles to each other, it’s possible to keep a pretty detailed map of where our bodies are in three dimensions. Also, when a fossil of a skull of some animal is found, if the semicircular canals are at right angles, you can conclude that the animal that owned the skull walked upright.
When you spin in a circle, the fluid in the canals starts moving. When you stop spinning, the fluid continues to move for a while and continues to send signals of movement to the brain. This makes you feel like you’re still spinning - you’re dizzy.
The third picture here shows the relative anatomy. Type in “inner ear” or “vertigo” into Google and you’ll get lots of hits.
BTW, alcohol diffuses into the fluid in the canals. It has a different density than the usual canal fluid and so causes disturbances in it. So, if you’ve had a lot of alcohol, the room starts to spin.