Hair grows on your head through a biological process beginning beneath the scalp where new cells form in the hair bulb, push older cells upward, causing them to harden and form a hair strand.
The Hair Growth Process Explained
Hair growth is a continuous cycle involving several key steps:
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Cell Production in the Hair Bulb: Deep within the hair follicle, at its base (the hair bulb), cells rapidly divide and multiply. These cells are the foundation of new hair.
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Keratinization: As the newly formed cells are pushed upwards, they become filled with a protein called keratin. This process, called keratinization, causes the cells to harden and die.
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Hair Shaft Formation: The hardened, keratinized cells become the hair shaft – the visible part of the hair. They are essentially dead cells, which is why cutting your hair doesn't hurt.
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Growth Cycle: Hair grows in cycles that include:
- Anagen (Growth Phase): This is the active growth phase, lasting several years. The longer the anagen phase, the longer the hair can grow.
- Catagen (Transition Phase): A short transitional phase where hair growth slows and the follicle shrinks.
- Telogen (Resting Phase): A resting phase where the hair doesn't grow and eventually sheds, making room for a new hair to start growing.
- Exogen (Shedding Phase): A part of the telogen phase when the hair sheds. This allows a new hair strand to begin the anagen phase and push the old strand out.
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Sebum Production: Sebaceous glands near the hair follicle produce sebum, an oily substance that helps to moisturize and protect the hair shaft.
In short, your hair grows because of continuous cell division at the root, which pushes older cells upwards to form a hardened strand of hair that emerges from your scalp. This process is cyclical, with periods of growth, rest, and shedding.
