Why Does Hair Keep Growing?

Explains Biplab Das

It is really intriguing that hair, although it is composed of dead cells, keeps growing. The secret of its growth lies in the hidden part of the hair, which remains under the skin. Hair originates from a ring of dividing cells, which later die out and contribute to its growth. At the base of dermis (there are two distinct layers of skin, inner dermis and outer epidermis) the seed of growth is sown as a cluster of dividing cells in a follicle. 

These cells divide continuously depending on the nutrients and oxygen supplied by the dermal tissue and blood vessels that surround the dividing cells. In the follicle, nascent cells move upward through the center. The innermost cells die and harden into hair while the rest also die giving rise to a double-layered hair sheath. Every dead cell adds to the length of the hair. 

Just before it sprouts through the skin, hair is bathed in oil from the sebaceous gland, which secretes oily matter. Hair growth may be affected by factors like nutrition, temperature, hormonal imbalance and diseases. But the popular notion that cutting helps hair growth is wrong.