Why does hair grow?
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Transcript
Your hair just keeps getting longer and longer, huh? Why does it do that?
Deep at the root of your hair, there's a spot that makes new hair. Tiny little cells there keep multiplying, more and more.
Those new cells become hair and push upward, little by little. That's why your hair gets longer, starting right from the root.
After growing for a while, the root sometimes takes a rest. When a hair falls out, a brand new one starts growing from that same spot.
Hair grows because new hair is made at the root, right where it starts.
For grown-ups: the science
Hair grows because new hair keeps forming at the root and gets pushed up and out.
Cells in the hair follicle's root, called the hair matrix, divide and fill with keratin as they push upward and harden. The visible part of hair is mostly these hardened cells, while the living cells at the root are what drive its growth. Hair also follows a cycle of growing, resting, and shedding, with new hair replacing the old.