It happens all the time when you get chilly. Those hairs on your arm stand up and you get goosebumps. What causes this though?!
It’s all thanks to something called the Arrector pili muscles. They are fan-shaped muscles at the base of each hair follicle. These cause the goosebumps. The way it works is that these muscles contract when the body is cold. They’re trying to generate heat and cause your hair to “stand up straight” on their skin. Actually a pretty cool way that nature is protecting you.
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