Hair Structure
HairnSenses explains about the proper
hair structure here. You can get all important points about hairs in man. Dr.
Sangay who is the most experienced surgeon in best hair transplant clinic in Delhi which is
known to be Hair & Senses. Here are some points:
1). A hair can be defined as a
slender, thread-like outgrowth from a follicle in the skin.
2). The hair is present
all over the body, except for the sole, palm, lips.
3). Hair is composed of
structural protein called keratin.
This is the same kind of protein that makes up the nails and the outer layer of
skin.
Hair
comprises of three morphological regions—the cuticle, medulla, and cortex
2. The middle layer known as the cortex. The
cortex provides strength, color and texture of the hair.
Structure
of the hair root
Hair root lies below the skin,
which is enclosed within a follicle. At the base of hair
follicle is the dermal papilla. The dermal papilla is fed by the
blood vessels which carries nourishment to produce new hair. The dermal papilla
is very important for the growth of the hair as it contains receptors for male
hormones and androgen's. The presence of these receptors is responsible for the
androgenic alopecia.
Hair
growth cycle
Hair on the scalp grows at a rate of about 6 inches/ year.
At any given time, a random
number of hairs will be in various stages of growth and shedding.
There are three stages of hair
growth: catagen, telogen, and anagen.
Anagen
Phase
The anagen phase is known as
the growth phase. It begins in the papilla and can last from two to
six years. The span at which the hair remains in this stage of growth is
determined by genetics. The longer the hair stays in the anagen phase, the
faster and longer it will grow. During this phase, the cells in the papilla
divide to produce new hair fibers, and the follicle buries itself into the dermal layer
of the skin to nourish the strand. About 85% of the hairs on one's head are in
the anagen phase at any given time.
Catagen
Phase
The catagen phase, also known
as the transitional phase, allows the follicle to renew itself. It
lasts for about two weeks. During this time, the hair follicle shrinks due to
disintegration and the papilla detaches, cutting the hair strand off from its
nourishing blood supply. Ultimately, the follicle is 1/6 its original length,
causing the hair shaft to be pushed upward. While hair is not growing during
this phase, the length of the terminal fibers increases when the follicle
pushes them upward.
Telogen
Phase
During the telogen, or resting phase the follicle
remains dormant anywhere from 1–4 months. 10 to 15% of the hairs on one's head
are in this phase of growth at any given time. In this phase the epidermal
cells lining the follicle channel continue to grow as normal and may accumulate
around the base of the hair, temporarily anchoring it in place and preserving
the hair for its natural purpose without using the body's resources.
The anagen phase begins again
once the telogen phase is complete. The dermal papilla and the base of
the follicle join together again and a new hair begins to form. If
the old hair has not already been shed the new hair pushes the old one out and
the growth cycle starts all over again. The process results in normal hair loss
known as shedding.