Eli5: Why do our faces pale when we faint?
In: Biology
Your face doesn’t pale *because* you faint, or vice versa. Both are symptoms of the same thing: A sudden reduction in blood flow to the head. As you may be aware, blood is red. Your skin, meanwhile, is probably a colour, and if it isn’t a colour, you may have accidentally misplaced it. More importantly, it’s partially transparent, so the red of the blood that flows through your face-meat is partially visible through your skin and gives the appearance of making your skin darker.
Blood also has another job besides making you look less like a corpse: it supplies oxygen and nutrients to the brain. Should the brain not get enough of either of those things, then it will stop working properly and may temporarily fail to produce the experience of being conscious – you may faint. When blood flow is suddenly reduced in the head, the face becomes paler because there’s less redness behind it, and the brain becomes unconscious-er because there’s less oxygen and sugar reaching it.
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