If hair is dead, how does it grow?

Do you know why it doesn’t hurt to get a haircut? Because the hair on your head is actually dead. But if it’s dead, how does it grow? Dermatologist Roxana Daneshjou explained it to us. Send your hairiest questions for Moment of Um to BrainsOn.org/contact , and we’ll comb for the answers. See omnystudio.com/listener for privacy information.