Hair disorder

Hair Bulb

The Hair Bulb is the lower part of the hair follicle, located at the base of the follicle. It is a structure of actively growing cells, which produce the hair shaft and the inner root sheath. The hair bulb is an essential component of the hair growth cycle and plays a crucial role in the production and growth of hair.

Structure

The hair bulb encompasses the hair papilla, a small, nipple-like extension of the dermis into the hair follicle. The hair papilla is made up of connective tissue and a capillary loop, which supplies nutrients to the cells of the hair bulb. Surrounding the hair papilla is the matrix, a germinal layer of cells responsible for the production of the hair shaft and the inner root sheath.

Function

The primary function of the hair bulb is to produce new hair through the process of keratinization. This process involves the transformation of matrix cells into hard, keratinized cells that form the hair shaft. The hair bulb also contains melanocytes, which are cells that produce melanin, the pigment that gives hair its color.

Hair Growth Cycle

The hair bulb plays a vital role in the hair growth cycle, which consists of three phases: anagen (growth phase), catagen (transitional phase), and telogen (resting phase). During the anagen phase, the cells in the hair bulb rapidly divide to form new hair. In the catagen phase, hair growth slows and the hair follicle shrinks. During the telogen phase, the hair follicle is at rest and no new hair is produced.

Clinical Significance

Changes in the hair bulb can lead to various hair disorders, such as alopecia, hirsutism, and telogen effluvium. For instance, damage to the hair bulb can result in hair loss or thinning. Furthermore, abnormalities in the hair bulb's melanocytes can lead to changes in hair color or the development of gray hair.

See Also

• Hair Follicle
• Hair Growth Cycle
• Keratinization
• Melanocytes