How Does Hair Know When to Stop Growing?
The hair on your scalp can get really long, but your leg hair doesn't sweep the floor. Why not? Hosted by: Hank Green ---------- Dooblydoo thanks go to the following Patreon supporters --...
==========
You’re probably quite happy that your armpit hair isn’t dragging on the floor.So it’s good that there’s a system to prevent that.But what is that system?Us humans grow hair all over our bodies -- except on our palms and the soles of our feet.But some of it, like leg hair, stops growing, while the hair on our heads just seems togrow out forever.That’s because every hair on your body goes through the same cycle -- growing for a whileand then falling out -- but each type of hair spends a different amount of time growing,and grows at a different speed.Every hair begins the same way, in a phase of the cycle called anagen.During anagen, blood flow starts to ramp up at the base of the follicle, feeding oxygento specialized stem cells. These cells begin rapidly dividing...
==========
You’re probably quite happy that your armpit hair isn’t dragging on the floor.So it’s good that there’s a system to prevent that.But what is that system?Us humans grow hair all over our bodies -- except on our palms and the soles of our feet.But some of it, like leg hair, stops growing, while the hair on our heads just seems togrow out forever.That’s because every hair on your body goes through the same cycle -- growing for a whileand then falling out -- but each type of hair spends a different amount of time growing,and grows at a different speed.Every hair begins the same way, in a phase of the cycle called anagen.During anagen, blood flow starts to ramp up at the base of the follicle, feeding oxygento specialized stem cells. These cells begin rapidly dividing...
