Human Anatomy – Hair
- Human Anatomy – Tonsils
- Human Anatomy – Teeth
- Human Anatomy – Stomach
- Human Anatomy – Tongue
- Human Anatomy – Esophagus
- Human Anatomy – Liver
- Human Anatomy – Gallbladder
- Human Anatomy – Spleen
- Human Anatomy – Pancreas
- Human Anatomy – Appendix
- Human Anatomy – Intestines
- Human Anatomy – Colon
- Human Anatomy – Abdomen
- Human Anatomy – Penis
- Human Anatomy – Bladder
- Human Anatomy – Kidneys
- Human Anatomy – Prostate
- Human Anatomy – Vagina
- Human Anatomy – Heart
- Human Anatomy – Skin
- Human Anatomy – Aorta
- Human Anatomy – Thyroid
- Human Anatomy – Lungs
- Human Anatomy – Brain
- Human Anatomy – Eyes
- Human Anatomy – Ears
- Human Anatomy – Sinuses
- Human Anatomy – Trachea
- Human Anatomy – Blood
- Human Anatomy – Rotator Cuff
- Human Anatomy – Shoulder
- Human Anatomy – Feet
- Human Anatomy – Hair
- Human Anatomy – Achilles Tendon
Society places utmost importance on hair, but it is, essentially, dead. All the hair visible on your body is made of dead cells, explaining why you don’t feel pain whenever someone cuts it.
Still, hair has many important bodily functions. For example, the eyebrows shield the eyes from sweat, while eyelashes defend them from excess dust and light. The hair on the head serves to cushion the skull and relatively protects the head from cold temperature.
Each strand of hair is rooted firmly in a so-called hair follicle, beneath which is the hair bulb or root. Keratin, the protein which makes up hair, is manufactured here. Blood vessels feed the keratin-building cells and supply hormones that modify the structure of the hair as you age. This way, hair keeps on growing.
Each hair follicle is adjoined to a sebaceous or oil gland. It secretes oil, giving hair its trademark luster and making it waterproof to an extent. During puberty, these glands can become overactive, secreting too much oil and making the hair greasy.
Whenever hair grows, it rises from the bulb and out the follicle. Upon reaching skin level, the cells in the hair die.
Growing hair goes through three stages. Initially it undergoes the anagen phase, or years of continuous growth. After this comes catagen, a phase when growth slows down, the follicle getting smaller. Telogen, the succeeding phase, is characterized by a stop in hair growth, the hair detaching from the follicle. This phase usually takes months. Hair then starts to grow again.
Speed of hair growth varies among people. On average, a person grows around half an inch of hair every month.
Hair color also varies among people too. The natural color of the hair is dictated by the pigment cells in the follicle. As you grow older, these cells expire, turning hair grey.
Hair diseases and conditions
Men are more likely than women to suffer from baldness. In male pattern baldness, men lose their hair in the crown, around the hairline, or both.
Sometimes, the baldness is only temporary, as in most cases of alopecia areata. This condition manifests itself with round balding patches on the scalp.
Surgery and extreme stress are known to cause hair loss, a condition known as telogen effluvium. The loss often happens at least a month after the event. Childbirth may also cause a form of telogen effluvium known as postpartum alopecia. In most of these cases, hair usually grows back fast.
Unlike men, women tend to confine hair loss around the scalp, though it may also spread to the crown. For the most part, balding women preserve their hairline. Female baldness is generally not as extensive as in males.
There are many cases where women grow hair on areas otherwise reserved for men, i.e. the face. This condition, called hirsutism, stems from heightened levels of testosterone in women.
Both sexes, however, may suffer from the common dandruff. Known medically as seborrheic dermatitis, dandruff involves itchy, inflamed skin on the scalp that comes off in flakes. Dandruff can affect the face and ears too.
Meanwhile, children are known to harbor lice in their hair. These insects suck blood from the scalp. They multiply fast and easily spread through proximity.
Apart from parasitic insects, hair can also serve as a breeding ground for fungi. One is tinea capitis or ringworm, which results in round patches of thinning hair. Contrary to its name, tinea capitis is not a worm. Another notable fungal infection is trichomycosis nodularis, which builds nodules around the hair’s fiber. Hair loss may result.
Bacteria can even undermine the hair. In one bacterial infection, called folliculitis, the hair follicles become inflamed, often due to Staphylococcus aureus. Acne is actually a kind of folliculitis, at times made worse by the bacterium Propionibacterium.
For some reason, some people could not help pulling out their hair. This is a mental disorder called trichotillomania, which always leads to hair loss. Scientists have yet to determine its cause.
Treating hair conditions
If you find yourself balding, you may resort to surgical hair transplants for cosmetic purposes. Otherwise, you can take natural supplements as a preventive measure, if not as a healthy lifestyle habit of sorts, against losing hair. It’s a natural remedy for age-related hair loss and thinning to help promote healthy natural hair regrowth.
On the flipside, you can remove hair permanently via several methods, like laser hair removal. Laser effectively obliterates cells in the hair follicle, nipping hair growth. Alternatively, you can have your hair removed through electricity. This procedure, called hair electrolysis, bombards the follicle with electric current via a metal needle.
Tests for hair conditions
Medical experts can use hair to test your exposure to toxic chemicals like mercury and lead. However, such tests could be inconsistent and misinterpreted.
Many crime scene investigators use hair follicles for DNA tests. These tests are commonly used to trace one’s paternity.
In addition, hair can also be used for drug tests. Apparently, hair easily absorbs illegal substances or their byproducts in the body.