Hair Follicle

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A Hair Follicle is an anatomical organ that is intended to grow hair filaments.



References

2023a

  • (ChatGPT OpenAI, 2023) ⇒ https://chat.openai.com/
    • A hair follicle is a small, tubular structure within the skin responsible for producing hair. It is a part of the integumentary system, which includes the skin, hair, nails, and associated glands. Hair follicles consist of various components, such as the dermal papilla (which provides nutrients), the hair matrix (where hair cells are produced), and the hair bulb (where hair growth occurs). Hair follicles also contain sebaceous glands that secrete sebum, which lubricates and protects the hair and skin, as well as the arrector pili muscle, which causes the hair to stand on end when contracted.

       Melanocyte stem cells are specialized cells that reside in the hair follicle, particularly in the hair bulge region. These cells are responsible for producing melanocytes, which are the pigment-producing cells that give color to our hair and skin. Melanocytes synthesize melanin, a pigment that absorbs ultraviolet (UV) radiation and protects the skin from damage. In the hair follicle, melanocytes transfer melanin to the keratinocytes, which are the cells that form the hair shaft. As the hair grows, the melanin is incorporated into the hair, giving it its color. The type and amount of melanin produced determine the specific hair color (e.g., black, brown, blonde, or red).

2023b

  • (Wikipedia, 2023) ⇒ https://en.wikipedia.org/wiki/hair_follicle Retrieved:2023-4-20.
    • The hair follicle is an organ found in mammalian skin. It resides in the dermal layer of the skin and is made up of 20 different cell types, each with distinct functions. The hair follicle regulates hair growth via a complex interaction between hormones, neuropeptides, and immune cells.[1] This complex interaction induces the hair follicle to produce different types of hair as seen on different parts of the body. For example, terminal hairs grow on the scalp and lanugo hairs are seen covering the bodies of fetuses in the uterus and in some newborn babies.[1] The process of hair growth occurs in distinct sequential stages: anagen is the active growth phase, catagen is the regression of the hair follicle phase, telogen is the resting stage, exogen is the active shedding of hair phase and kenogen is the phase between the empty hair follicle and the growth of new hair.[1]

      The function of hair in humans has long been a subject of interest and continues to be an important topic in society, developmental biology and medicine. Of all mammals, humans have the longest growth phase of scalp hair compared to hair growth on other parts of the body.[1] For centuries, humans have ascribed esthetics to scalp hair styling and dressing and it is often used to communicate social or cultural norms in societies. In addition to its role in defining human appearance, scalp hair also provides protection from UV sun rays and is an insulator against extremes of hot and cold temperatures.[1] Differences in the shape of the scalp hair follicle determine the observed ethnic differences in scalp hair appearance, length and texture.

      There are many human diseases in which abnormalities in hair appearance, texture or growth are early signs of local disease of the hair follicle or systemic illness. Well known diseases of the hair follicle include alopecia or hair loss, hirsutism or excess hair growth and lupus erythematosus.

  1. 1.0 1.1 1.2 1.3 1.4 Blume-Peytavi, Ulrike (2008). Hair growth and disorders. Berlin: Springer. ISBN 9783540469117. OCLC 272298782.