|
 From
the shaved heads of medieval monks, to the long-haired hippies of the
'60s, to the spiked hairdos of today's punk rockers, hair has always
made a personal statement.
"It's one of the leading ways people can establish their individuality
and express their style," says Jerome Shupack, M.D., professor of clinical
dermatology at New York University Medical Center in New York City. "Hair
has had sociological importance throughout the ages."
Because of its importance, anything that happens to our hair that we
can't control--falling out or turning gray, for instance--can be the
source of much anxiety.
In the United States, some 35 million men are losing or have lost their
hair from male-pattern baldness, according to the American Hair Loss
Council. Approximately 20 million women have experienced a similar loss
of hair (from female-pattern hair loss), and an estimated 2.5 million
Americans have lost their hair due to other causes.
Hair is produced by hair follicles--indentations of the epidermis (outer
skin layer) that contain the hair root, the muscle attached to it, and
sebaceous, or oil, glands. Hair is made up of dead cells filled with
proteins, most of which are known as keratins. The cells are woven together
like a rope to form the hair fiber. The hair fiber, in turn, has three
layers: the outer cuticle with its fish-scale-like structure; the cortex,
which contains the bulk of the fiber; and the center, or medulla. Hair
color is determined by melanocytes, cells that produce pigment. When
these cells stop producing pigment, hair turns gray.
Although it seems as if the hair on your head is always growing, hair
actually has active and rest phases. The growth phase, known as anagen,
lasts for two to six years. At any given time, about 90 percent of scalp
hair is in the growth stage. The remainder is in the rest phase, known
as telogen; this lasts from two to three months.
Once the rest phase is over, the hair strand falls out and a new one
begins to grow. As a result, it's considered normal to lose from 20 to
100 hairs a day, says Diana Bihova, M.D., a dermatologist in private
practice in New York City. Only a change in your regular pattern of loss
is considered abnormal--but many things, including genetic factors, diet,
stress, and medications, can change that pattern. |
Chemotherapy & Side Effects
