Is Hair Made of Dead Skin Cells?

Many people mistakenly believe that hair is made of dead skin cells. However, the truth is more fascinating and intricate. While hair is indeed related to skin, it is primarily composed of a protein called keratin, which is produced by hair follicles. This article explores the structure and composition of hair, shedding light on why hair is made up of dead cells and how this relates to skin, keratin, and keratinization processes.

The Composition of Hair

Hair is not directly made of skin cells. Rather, it consists of several layers of dead, keratin-filled cells that are pushed out by living cells within the hair follicle. The hair shaft, the visible part of hair, is made up of these dead cells, but it is not formed from skin cells. Hair follicles, located in the skin, are responsible for producing and maintaining hair. The living cells within the follicle divide and push older cells upwards, where they harden and form the hair we see. Skin cells, on the other hand, are part of the epidermis, the outer layer of skin, but they do not directly contribute to the structure of hair.

The Process of Keratinization

As mature cells protrude from the follicle, they undergo a process called keratinization. During this process, the cells accumulate keratin, a protein that is responsible for the structural integrity of the hair. The nuclei of these cells eventually break down, making the cells appear dead. This hardening and transformation into keratin-filled cells create the keratin sulfate, the main component of hair, produced by Keratinocytes. Keratinocytes are present on the outermost side of the skin, known as the epidermis, and are among the most frequently dividing cells in the body. The number of keratinocytes directly impacts hair density, with more keratinocytes leading to denser hair.

The Layers of Hair

Hair is composed of three distinct layers, each serving a vital function in the structure and appearance of hair:

Cuticle

The cuticle is the outermost layer of hair and consists of several layers of flat, thin dead cells. This layer not only provides the shine and reflectivity we see in hair but also serves as a protective barrier, shielding the inner layers from damage.

Cortex

The cortex is the main bulk of the hair, containing the protein complex melanin, which gives hair its characteristic color. Melanocyte cells, present at the hair root within the follicle, produce melanin, contributing to the hair's pigment and overall appearance.

Medulla

The medulla is located in the center of the hair structure and can vary in presence and density. This open region serves as a core to the hair's fibres, playing a role in the hair's overall strength and resilience.

The Role of Cancer Treatment

It's worth noting that hair loss is a common side effect of cancer treatment, particularly chemotherapy. Chemotherapeutic drugs target dividing cells to slow down or stop the growth of cancer cells. However, they often fail to distinguish between cancer cells and rapidly dividing healthy cells. Due to the high division rate of Keratinocytes, these cells are frequently targeted by the drugs, leading to hair loss. This phenomenon highlights the crucial role of keratinocytes in hair structure and the importance of understanding the biological processes involved in hair growth and maintenance.

Conclusion

In conclusion, hair is not made of dead skin cells but rather of keratin-filled, dead cells that are produced by hair follicles. These cells undergo the process of keratinization, which is essential for the formation and maintenance of hair structure. Understanding the components and layers of hair not only sheds light on its physical properties but also underscores the biological significance of these processes in human physiology.