While hair may seem lifeless, this is only partially true. The hair we see and style everyday lacks sensation, but each strand originates from intricate biological processes beneath the skin’s surface. Understanding the distinction between living and non-living hair components offers a complete picture of how our bodies produce hair.
The Living and Non-Living Parts of Hair
Hair growth begins within a specialized structure called the hair follicle, embedded in the skin. This follicle represents the living part of hair, functioning like a miniature organ responsible for hair production. At the base of the follicle lies the hair bulb, which surrounds the dermal papilla. The dermal papilla contains blood vessels that deliver nutrients and oxygen to the rapidly dividing cells in the hair bulb.
These cells, known as keratinocytes, continuously multiply and push upwards. As they move away from the nutrient supply in the dermal papilla, they undergo a process called keratinization. During this process, the cells fill with a tough, fibrous protein called keratin and lose their nucleus and cytoplasm. By the time these cells emerge from the scalp, they are no longer alive.
The visible part of the hair, known as the hair shaft, is entirely composed of these dead, keratinized cells. Each hair shaft consists of three main layers: the medulla, cortex, and cuticle. The outermost layer, the cuticle, is made of overlapping, scale-like cells that protect the inner layers. Since the hair shaft lacks metabolic activity, it cannot heal itself from damage or grow new cells.
Why Understanding This Matters for Hair Care
Understanding that the hair shaft is non-living profoundly influences effective hair care practices. Because the visible hair cannot repair itself, damage such as split ends or breakage becomes permanent until the hair is cut. External factors like heat styling, chemical treatments, and environmental exposure can degrade the protective cuticle layer, leading to further damage to the inner cortex.
Proper hair care therefore involves a dual approach: nourishing the living components and protecting the non-living hair shaft. Scalp health is important, as it houses the hair follicles and their blood supply. Maintaining a healthy scalp environment supports the optimal functioning of the hair follicles, which are responsible for producing new, healthy hair strands.
Protecting the existing hair shaft from damage involves minimizing exposure to harsh chemicals and excessive heat, which can weaken the hair’s structure. Using gentle products and protective measures can help maintain the integrity of the hair’s outer cuticle, reducing friction and preventing further wear and tear on the already formed, non-living strands.