HAIR THEORY
Hair, you cut it and it grows again! It becomes damaged either by nature or improper care and it
can be reconditioned. Its color can be changed and it can take on straight, wavy or curly shapes.
The main purposes of hair are protection from heat, cold and injury, as well as adornment.
But have you ever wondered what makes all this possible? The answers lie in the marvelous, mys-
terious biology of living matter or, for your purposes of study,
Trichology, the technical name for
the study of hair.
Living matter. What does it mean to say that something is alive? By definition, to say that matter
has life means that it grows, it can reproduce, and it responds to stimulation. That is, it can act. It
can react.
Is hair alive? Even though hair is primarily protein and protein is the basis for all living matter,
only
the cells of the hair bulb are alive. The hair fiber or strand itself is not alive.
Hair Bulb Formation
To understand more about hair, you need to know
how the hair bulb is formed. In fetal life,
the hair
follicle forms from a cluster of cells in the upper
layer of skin
, technically referred to as the basal
layer of the epidermis. This cluster of cells, called
the primitive hair germ, needs nourishment to grow
into a fully developed hair follicle. To get nourish-
ment, it works its way down into the lower (dermal)
layer of the skin. As it does, the cell cluster pulls the
upper layer down with it, creating
a follicle or
tube-like "pocket" called the root sheath, out of
which the hair will grow.
The shape of this follicle will determine the shape (round, oval, ellipti-
cal, etc.) of the hair shaft as it grows from the follicle
.
Since the hair
shaft actually grows out of the hair follicle
, the diameter of the hair fiber
will be the same as the diameter of the inside of the follicle.
In straight or wavy hair, hair follicles
are more or less vertical to the
surface of the scalp, with a slight
"tilt." The angle of the hair follicle
determines the natural flow or wave
pattern of the hair.
The follicle in
straight or wavy hair is typically
round or oval.
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TRICHOLOGY
Primitive
Hair Germ
Basal
Layer
Hair
Follicle
Start of
Sebaceous Gland
and
Arrector Pili
Muscle
Papilla
Two Primary Parts of Hair
The hair root is the portion
of hair that is inside the hair
follicle
under the skin's sur-
face. The hair fiber, some-
times referred to as the
hair
shaft or strand, is the portion
of the hair that extends above
the skin's surface.
round
oval
elliptical
Hair
Bulb
Hair
Bulb
Hair
Bulb
