Hair Anatomy and Physiology

Hair anatomy and physiology

Hairs are horny filaments formed by test tube-shaped invaginations of the epidermis. The portion protruding obliquely from the skin is called the hair shaft. Inserted into the skin and extending to the subcutis is the so-called hair follicle. The hair also includes the sebaceous glands, which open into the hair funnel, as well as the hair muscle Musculus arrector pili, which erects the hair and is responsible for the formation of goose bumps in cold or emotional conditions. At the lower end of the hair is the hair bulb, into which the hair papilla extends from the dermis and is responsible for the blood supply from blood capillaries. Here the hair shaft is formed by matrix cells. They are comparable to the stratum basale of the epidermis. The hair itself consists of the cuticle (scale layer), the hair cortex (cortex, fibrous layer) and the hair marrow (medulla). The hair shaft, like dead cells, is composed of hard keratin, a fibrous protein with a high content of the amino acid cysteine, which is also an essential component of the epidermis and nails. The hair of the scalp grows about 1 cm per month. Hair color is due to melanins, which are deposited at the base by melanocytes. When graying, this storage stops. There are about five million hair follicles distributed over the entire body. Hair has a protective and communication function, serves as a sensory organ and is important for thermoregulation.

Cyclic hair growth

Hair growth is a cyclic process in which each hair follicle goes through three phases. The vast majority of follicles in the scalp hair are in the growth phase (anagen), which lasts from 2 to 7 years. The subsequent regression phase (catagen) is short and lasts only 2 to 3 weeks. At the end of the resting phase (telogen), which lasts 2 to 4 months, the hair is shed. Every day we lose about 50-100 of our 100,000 head hairs. Hair growth is asynchronous because each follicle goes through the cycle independently of its neighboring follicles and therefore only a few hairs fall out each day and not all at the same time!

Hair loss

Hair problems and diseases

  • Dandruff
  • Greasy hair
  • Brittle hair
  • Dry hair
  • Gray hair
  • Too little volume
  • Split ends, damaged hair
  • Head lice, body lice, crabs.
  • White spots (vitiligo)
  • Scalp eczema
  • Wigs, hair transplant
  • Acne
  • Hypertrichosis
  • Hirsutism

Medication and dietary supplements