As a subject matter expert in biology, I can provide a comprehensive answer to your question regarding the nature of hair. Hair is indeed a fascinating structure that is both a part of our body and yet, in a way, not quite "alive" in the traditional sense.

Firstly, it's important to understand the structure of hair. Hair grows from hair follicles, which are tiny structures in the skin that produce hair. These follicles are connected to blood vessels that supply them with the nutrients necessary for hair growth. The base of the hair, where it is attached to the follicle, is indeed living tissue. This is because it is part of the living cells of the body that are constantly dividing and growing.

However, as the hair grows and emerges from the skin, it changes. The cells that make up the hair shaft, the visible part of the hair, are no longer living. They are essentially dead cells that have undergone a process called keratinization, where they become filled with a protein called keratin. This process makes the hair strong and provides it with its characteristic structure.

The process of hair growth can be broken down into three phases:


1. Anagen (Growth Phase): This is the active growth phase where the hair follicle base is producing new cells. These cells push the older cells up the hair shaft, causing the hair to grow longer.


2. Catagen (Transition Phase): This is a short transition phase where the hair follicle shrinks and detaches from the blood supply, stopping the growth of the hair.


3. Telogen (Resting Phase): The hair follicle rests, and the hair strand is eventually shed to make way for new hair growth.

So, to answer your question directly, the part of the hair that is beneath the skin, in the follicle, is living. But the part of the hair that you can see and touch, the hair shaft, is dead. It's composed of dead keratinized cells that have been pushed out of the follicle as new cells form beneath them.

Now, let's transition to the Chinese translation of the answer.

read more >>

Tiny blood vessels at the base of every follicle feed the hair root to keep it growing. But once the hair is at the skin's surface, the cells within the strand of hair aren't alive anymore. The hair you see on every part of your body contains dead cells.read more >>