Transcript Hair and Scalp 1030

Hair and Scalp Care 1
HSA3400
•The study of the hair is
called Trichology
• The chief purposes of hair are
adornment and protection.
• Hair is composed mainly of a
protein called keratin.
Full-grown human hair is divided
into two principal parts:
• The Root – which is the portion of the hair
located beneath the skin’s surface; this is
the portion of the hair enclosed within the
follicle.
• The Hair Shaft – is the portion of the hair
structure extending above the skin’s
surface.
Structures associated with the hair root
are the follicle, bulb, and papilla.
• The follicle is a tube-like depression in the scalp
or skin that encases the hair root.
• The bulb is a club-shaped elevation located at
the bottom of the hair root.
• The papilla is a cone-shaped elevation located
at the bottom of the hair follicle and fits into the
hair bulb. The papilla contains a rich blood and
nerve supply that contributes to the growth and
regeneration of the hair.
follicles are the arrector pili and
sebaceous gland.
• The arrector pili is an involuntary
muscle attached to the underside of the
hair follicle.
• The sebaceous is an oil gland
connected to the follicle. It produces
sebum (oil) that keeps the skin soft and
supple.
The layers of the hair are:
• Cuticle – outside layer composed of overlapping
scales that protect the inner layers.
• Cortex – inner layer which gives strength and
elasticity. The cortex also contains pigment
called melanin.
• Medulla – innermost layer that determines the
thickness of individual strands of hair. The
medulla may be absent in fine hair.
• Location
We have hair over most of our bodies except for the
palms of the hands, soles of the feet, the lips, and a few
other very small areas.
There are two types of hair:
• Languo – all over the body, it is fine, un-pigmented hair.
• Terminal – found on the scalp, face, and extremities; it is
coarser hair.
• What is hair texture?
TEXTURE
• It is the diameter of the hair. Fine is
smaller and thinner in diameter. Medium
is larger that fine hair. Coarse is larger
than medium hair. There are two
structures that influence the diameter of
the hair: the medulla and the cuticle.
Texture is very important when selecting
products.
• Porosity refers to the amount of moisture
that can be absorbed by the cuticle layers.
•
Elasticity refers to the hair’s ability to
stretch without breaking and then return to
its original form.
• Density refers to the number of hairs per
square inch.
Cycles of Growth
• The first hair appears in the sixth or seventh week after conception.
All human growth cycles differ from one region of the body to
another. Scalp hair grows 2-5 years, hair on the trunk, limbs, etc.
occurs 4-6 months. The three cycles of growth are Anagen,
Catagen, and Telogen (A.C.T.)
• Anagen – first period when the hair bulb stretches itself out into the
follicle. The second period is when keratin is being synthesized in
the follicle (2-5 years).
• Catagen – hair growth slows and club hairs form. Keratinization
does not take place during this stage.
• Telogen – resting period that continues until the next anagen stage
begins, it lasts about 3-4 months.