What causes people to pass out on fast rides?
In: Biology
The heart pumps blood to the brain to keep you conscious. The brain is located higher in your body than your heart, so the heart usually has to pump against gravity to get blood to your brain. This usually isn’t much of a challenge for the heart in a healthy person, but it still requires the heart to pump at a high enough pressure to overcome gravity.
Now, when you’re on a rollercoaster ride, the heart has to pump against a much greater force. Newton’s third law states that for every force acting on an object, there is an equal and opposite force. So that means that, while there is a great force lifting you up into the air, there is also a great force pushing you down into the seat.
This force doesn’t just affect your outer body, but also your blood. So your heart essentially has to pump against gravity plus the force lifting you up, which is much harder. When not enough blood can get to your brain, the part of your brain that keeps you awake shuts down to keep you alive by using the blood on the parts of the brain that keep your internal organs going.
You’re also more likely to pass out if you’re screaming a lot or if you’re very scared. This is because, in these situations, your blood vessels become narrower, so even less blood can get through to your brain.
On the other hand, genetics and training can reduce this effect by making your heart better at pumping blood.
Rapid upward acceleration (like at the bottom of a dip or a spiraling coaster) causes blood to flow down, which means the brain gets less blood. Jet pilots wear suits that put pressure on the lower body, which keeps more blood in the upper body, and therefore the brain.
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