For many, hair can be source of worry as well as jealousy at times. For some, it is source of vanity too. If people have correct information and facts about hair, they will be spared of much worry or jealousy.
An average person has up to 150,000 hair follicles on one’s head, whereas the entire adult body has 5 million. That number is constant over a lifetime. Hair has two distinct structures – the follicle itself, which resides in the skin, and the shaft, which is what is visible above the scalp.
Hair follicle – The hair follicle is a tunnel-like part of the epidermis that extends down into the dermis of the skin. At the base of the follicle is the papilla, which contains capillaries, or tiny blood vessels that nourish the cells. The living part of the hair is the very bottom part surrounding the papilla, called the bulb. The cells of the bulb divide every 23 to 72 hours, remarkably faster than any other cell in the body. Only one hair grows out of one follicle. At the base of the hair follicle are sensory nerve fibers that wrap around each hair bulb. Bending the hair stimulates the nerve endings allowing a person to feel that the hair has been moved.
Hair follicle has two sheaths, which protect it and help form the growing hair shaft. There are several other structures associated with the hair follicle, including arrector pili, which is a tiny bundle of muscle fiber connected to a follicle. The contraction of these muscles is what causes goose bumps. Sebaceous glands are also attached to hair follicles, which produce oil, called sebum that moves up hair follicles to the surface of the skin, where it lubricates skin and hair.
Hair shaft – The hair shaft is made of a hard protein called keratin and is made of three layers. In fact, the hair is not a living structure as this protein is dead. The inner layer of a hair is the medulla, the second layer the cortex and the outer layer the cuticle. The cortex makes up the majority of the hair shaft. The cuticle is a tightly formed structure made of shingle-like overlapping scales. It is both the cortex and the medulla that holds the hair’s pigment, giving it its color.
Hair growth cycle –
There are four stages of hair growth cycle:
• Anagen (Growing phase): Hair in the anagen phase may grow faster during the early years. Average growth rate is 1 – 1.5 cm per 28 days. This phase lasts for two to seven years and determines the length of our hair.
• Catagen (Regression phase): This stage lasts about ten days. The hair follicle shrinks and detaches from the dermal papilla.
• Telogen (Resting phase): This is the resting phase of the follicle which lasts for approximately four months. About 10 to 15% of hairs are this stage. The follicle remains quiescent in its shortened state and awakens to regenerate with the onset of the new growth phase.
• Exogen (Shedding phase): This is the period in which hair reaches its terminal position in the follicle. The resting hair is gradually loosened resulting in its shedding. The majority of shedding occurs during new growth phase.
Over time, the length of the anagen stage decreases. Therefore, the hair may become weaker and thinner after each cycle. That’s why it’s important to ensure your diet is rich in specific nutrients to maintain normal, healthy hair growth.
If hairs enter the resting phase too early, excess shedding and noticeable thinning of the hair can occur.
Telogen effluvium –
Telogen effluvium is a phenomenon that occurs after pregnancy, major surgery, drastic weight loss, or extreme stress, in which people shed large amounts of hair every day, usually when shampooing, styling, or brushing. It can also be a side effect of certain medications, such as antidepressants, beta-blockers, and non-steroidal anti-inflammatory drugs. During telogen effluvium, hair shifts faster than normal from its growing phase into the resting phase before moving quickly into the shedding, or telogen, phase.
The bottom line –
Hair is far more complex than most of us understand. Besides creating gender identity, it plays a vital role in the appearance of both men and women. Therefore, any factual information about hair will help people take good care of them.
The structure of hair is quite complex than it is mostly understood by people. It is also important to understand its process of growth because it will shed light on why hair fall occurs and number of hair fall that should be considered normal. This will reduce the anxiety of many people about their hair fall.