Unlike most warm-blooded land animals, humans have no fur to keep them warm – most of the hair that covers our bodies is very fine. Bare skin is good for keeping the body cool, but in colder climates, humans need to wear clothes to maintain their body temperature.
Hair growth
Each hair grows out of a deep, narrow shaft called a follicle. At the base of the hair, living cells divide and push the hair upwards. Hair does not grow constantly. Instead it grows in spurts and has periods of rest in between.
- Active follicle: The active follicle creates new cells inside the hair root. As these die, they are pushed out to form the shaft, which gets longer and longer.
- Resting stage: The follicle becomes narrower, and the hair stops growing. The hair gets pulled away from the root, losing its blood supply.
- New growth: The follicle begins a new cycle. As people age, their hair becomes thinner because fewer follicles reactivate and grow new hairs.
Picture Credit : Google