Here's a breakdown:
* Hair Root (Located within the follicle under the skin):
* Contains living cells, including those in the hair bulb at the base of the root.
* Cells are actively dividing and growing in the hair bulb.
* Contains the hair papilla, a structure at the base of the hair bulb that provides nutrients and signals for hair growth.
* This area is responsible for producing new hair cells.
* Hair Shaft (Visible part of the hair above the skin surface):
* Consists of dead, keratinized cells.
* These cells have matured, hardened, and become filled with keratin (a tough protein).
* Lacks a blood supply or nerve endings.
* Because the cells are dead, the shaft is insensitive to pain and cannot repair itself.
The specific point where this transition occurs is within the hair follicle, specifically in the keratogenous zone. The Keratogenous zone is the location within the hair follicle where the cells are rapidly dividing, differentiating and keratinizing into the hair shaft.