Hair, there and everywhere...............

HAIR STRUCTURE

Hair is made up of dead, keratinised structures which are formed within
the dermis of the skin in a small sac-like follicle. The follicle can
first be seen as a surface indentation of the epidermis layer. The
follicle is made up of two layers; the outer layer is comprised of
fibrous tissue with abundant nerves and is highly vascular.
The inner layer is made up of two layers of cells known as the outer
and inner root sheath. The outer root sheath forms the root of the
follicle.
The inner root sheath is made up of three layers of cells. Some of
these cells contain a flattened nucleus whereas other cells do not.
Elongation to the follicle occurs as the hair grows longer and deeper.
This portion of the hair which grows inside the follicle is known as
the hair root. The root which is the lowest section of a hair enlarges
at the end into a soft, light-coloured structure called the hair bulb.
The papillia projects into the hair bulb at the base of the follicle.
Made up of connective tissue and blood vessels, the papillia supplies
nourishment (through the blood) for growing cells.
Keratin is produced when the cells from the hair bulb are pushed upward
as news ceils form from beneath. The supply of nourishment is cut off
as cells move higher up and a hard protein (keratin) begins to form.
Hair cells die as keratinization takes place. By the time the hair has
reached a third of the way to the surface, the keratinization process
has been completed. The part of the hair which has keratinized and
is now above the surface of the epidermis is known as the hair shaft.

TYPES OF HAIR

There are two tpes of hair in the human body; vellus and terminal. A
third type, known as lanugo hair, is present at the foetus stage but
this is soon cast after birth. Lanugo hair is usually the first sign
of cellular activity and is replaced with hair still fine in texture
but slightly coarser.

VELLUS HAIR:
Vellus hair is found all over the body apart from the soles of the feet
and palms of the hands. This hair type is downy/ soft, fine, fluffy
and a slow growth rate begins from a follicle that is very shallow.
The sebacceous gland supplies this type of hair with nourishment and
the vellus hair remains blonde in colour as these hairs do not normally
contain melanin. The medulla is absent in this hair type.

TERMINAL HAIR:
Hair found on the scalp, eyebrows, axillary and pubic regions are known
as terminal hairs. They have well developed bulbs as they are
nourished from the dermal papilli. Vellus hairs are not as deep set
as terminal therefore bulbs are not developed. Hair of this type grow
to longer lengths than vellus hair and is a lot thicker and coarser.

So much hair, here and there, so what do we call it:
Head capilli hair:
Eyelashes: cilia
Eyebrows: supercilia
Nostrils: vibrissae
Ears: tragi
Face: barba
Armpits: hirci
Pubic region: pubes

Terminal hair is made up of three concentric layers of cells. The
inner core is known as the MEDULLA (the centre layer). Keritinized
cells interspersed with air spaces comprise the medulla. Some of these
cells also contain air which supply terminal hair with pliablity and
lightens. These air cells are also involved in creating the various
colour tones of hair by influencing the reflection of light.
Surrounding the medulla is the CORTEX. This particular layer is
comprised of elongated cells which contain granules of the pigment
melanin. Melanin gives hair its colour but blonde or grey hair have
an absence of this pigment. Melanin does not always extend to the end
of the tip resulting in the hair tip appearing colourless. Air cells
replace the melanin in white or pale hairs.
The outer layer of the hair is known as the cuticle. This layer
consists of a single layer of fine transparent scales which overlap
each other and are flat.

Introduction to hair - "Hirsutism" or should it be Her-suit-like-him

Hirsutism is the term used to define excessive terminal hair growth in
areas of the body which are androgen sensitive. The growth pattern is
that to a males, and the condition is most distressing to females who
are sufferers. Hirsutism can disable a woman psychologically as
unwanted hair is seen as socially unacceptable in many societys. In
turn, male growth patterns of hair in females may socially inhibit both
the younger and older woman.
There are numerous factors which can cause hirsutism, the first being
the endocrine system. The hormone, androgen, is produced by the sex
glands in both male and female, and is the major contributing hormone
which determines hair growth distribution in both sexes.
Genetic influences are another factor. Distribution of hair varies
immensely among differing ethnic groups.
A third factor which effects superfluous hair growth is the aging
process. As the aging process progresses, bodily functions undergo
certain changes, eg: menopause. In fact, the body can go through
numerous hormonal changes, which result in physically noticeable
effects such as excessive hair growth. Pregnancy and adolescence are
some other examples.
There are various measures which delay and eventually cause hair growth
to become obsolete such as waxing, shaving and electrolysis. There is
some controversary about which local method is the best for permanent
results. However, if such methods are not satisfying then drug
treatments are available.