105E 03 Smart Notes PDF

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105E 03 Smart Notes...

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105 .3 HAIR THEORY E

ACHIEVE //

FOCUS //

Following this lesson on Hair Theory , you’ll be able to:

HAIR THEORY

• List the main structures of the hair follicle

Hair Structure

• Identify the three stages of hair growth and the factors that affect it

Hair Growth

• Describe the process of how hair gets its color

Natural Hair color

105 E.3

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T HEORY

SMARTNOTES

PAGES 32-33

Trichology is the study of hair

.

Main purposes of hair:

• adornment

• protection from heat cold and injury

• sensory perception

Hair is derived from the epidermis and consists of two distinct parts:

HAIR STRUCTURE

• whatever

• whatever

The hair follicle, the hairstrand, the arrector pili muscle and the sebaceous gland make up the idc

HAIR FOLLICLE

idc

.

Hair grows from the hair follicle which is a tube-like “ idc

.”

Hair is a complex structure that extends deep into the idc

.

3 SEGMENTS: idc

idc

Lower segment

•

•

Dermal idc

idc

•

Root idc

dci

•

Germinal idci

Middle segment •

•

Arrector pili dic

idci

Extends from insertion of arrector pili muscle to entrance of

• jfn

ihndoijqfj

Extends from base of follicle to insertion of

hindwo

Upper segment

•

• fhn

ihfeon

Extends from the entrance of sebaceous gland duct to opening of the ubd

( oinf

obfo

)

•

Filled with ohubu

DERMAL PAPILLA Dermal papilla: Mass of loose connective tissue located at the base of the hair follicle. •

Contains tiny capillaries (small blood vessels) that supply nourishment to the cells around it, called fhdb dhbiu

uhidbiu

.

105 E.3

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SMARTNOTES

PAGE 34

HAIR FOLLICLE (CONT’D) ROOT SHEATH The root sheath includes outer and inner portions that help form growing hair.

DESCRIPTION

FUNCTION

ibiub

•

STRUCTURE

Continuation of the b

Contains:

iu

•

• Surrounds the inner hbiv

iv

• ui •

•

Remains i

•

Serves as storage for viu

Melanocytes b

Merkel cells

bi

Inner Root Sheath

•

Structure in the lower part of

Three layers:

the iub

Henle’s Layer

ib

•

Outermost layer of the inner root sheath;

•

Surrounds and protects growing hair

single layer of cube-like cells with clear,

•

Helps hair take a ib

i

i

Huxley’s Layer •

Between the cuticle and ih

•

Contains 1-2 layers of flattened bi

b

bi

bi

iu

•

Lies in the

•

Forms the channel for u

•

Anchors hair in place

huiuh

GERMINAL MATRIX The germinal matrix is an area of cells around the dermal papilla. •

Often referred to as the iuh

•

Cell division (mitosis) takes place in this area of the

.

ARRECTOR PILI MUSCLE Arrector pili muscle: Isthmus or middle segment of the follicle. •

Extends from cells in the dermis to attach to the follicle just below the huihui

•

hui

.

Causes the hair to stand on end when a person is scared or

hui

105 E.3

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SMARTNOTES HAIRSTRAND (HAIR SHAFT)

PAGE 35 Hair root: Portion of hair inside the hair follicle hui hui

hui

the .

Hairstrand: Portion of hair that extends hui hu

the

hu

.

Keratinization: Process where cells change their shape, dry out and form uih

h

.

Once keratinized, the cells that form the hairstrand are no longer hu

.

Parts of the Hairstrand: ui

3. •

Central core of the hairstrand

•

Also called the pith or iu

•

Often absent in fine or very uih

2.

iuh

uih •

Second layer, consisting of unique ui

structures

• Gives hair most of its pigment and strength— u

1.

ui •

Outer covering of the hairstrand

•

Made up of overlapping layers of ui

ui

HAIR CLASSIFICATION The three major types of hair on the body are: Lanugo •

Baby-fine, silky hair on the body

hui •

Thin, short, fine, non-pigmented

at birth, shed shortly uih

hair found more abundantly on

uih

ui

iu •

Long, thick, pigmented hair like normal scalp and eyebrow hair after

Technical Hair Ter ms: Capilli: Hair that grows on the scalp Barba: Thick, coarse hair that grows on the face to form a beard Cilia: Eyelash hair Supercilia: Eyebrow hair

105 E.3

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SMARTNOTES

PAGES 36-37 Hair growth pattern and stage of growth relate directly to the way you

HAIR GROWTH

perform a temporary hair removal service or semi-permanent service such as uih

HAIR BULB FORMATION

.

The hair bulb forms at the base of the hair iu

.

Primitive Hair Germ

In fetal life, the hair follicle forms from a cluster of cells in the upper layer of skin,

Basal Layer

technically referred to as the stratum hiu •

This cluster of cells is called the hui ■ ■

Start of Sebaceous Gland and Arrector Pili Muscle

•

•

ui

.

u

.

To get nourishment, the primitive hair germ works its way down into the lower ) iu

.

As the primitive hair germ works its way down, the cell cluster pulls the upper layer down with it, creating a iuh

Hair Follicle

u

Needs nourishment to grow into a fully developed hair

( ihu •

uhi

.

At the base of the hair follicle is a large structure called the papilla, which supplies iuh

to the hair iuh

.

Papilla

SHAPE OF THE FOLLICLE

The shape of the hair follicle determines the shape (round, oval or elliptical) of the hairstrand as it grows from the follicle. Since the hairstrand grows out of the hair follicle, the diameter of the hairstrand will match the diameter of the iuh

of the iuh

.

Angle of the hair follicle determines the natural hair flow or uhi

Hair Type: Straight SKETCH THE SHAPE OF THE FOLLICLES

iu

Hair Type: Wavy to Curly

Follicle Shape:

Follicle Shape:

ui

hiu

.

Hair Type: Tightly Curled Follicle Shape:

Description:

Description:

Description:

The follicle in straight

hiuuhi

Hair follicles grow at a much stronger hui

hair is typically round or iu

.

.

105 E.3

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SMARTNOTES

PAGES 38-41

STAGES OF HAIR GROWTH THREE STAGES OF HAIR GROWTH

ANAGEN STAGE

CATAGEN STAGE

Active growing stage

Brief transitional period when all cell division stops

•

Each hair bulb has attached root hu

•

hu •

- huu

.

base of iiu

hui

.

•

Hair falls out at this time.

•

On average, 10%-15% of hair is in

end of the hair comes loose from

During this stage hair color is uih

.

Dermal papilla breaks away; lower

•

Hair bulb has no attached iuh

i

On average, 90% of hair is in this stage, which can last from

•

Lasts only a i

•

.

TELOGEN STAGE

the resting stage, which generally .

lasts uh

-uhi

iuh

.

.

Hair Facts •

The average rate of human hair growth is iuhu hiu

FACTORS THAT AFFECT HAIR GROWTH

(1.25 cm)

huh

.

•

Hair never grows on palms, soles of feet, lips or iiuh

•

Eyebrows and eyelashes are replaced every uhi

. - uhi

hu

.

Excessive hair growth on various areas of the body is classified as iu

or hu

.

Hirsutism

Possible cause:

Excessive amounts of terminal hair found in women in areas of the

Also known as:

Polycystic ovary

body where men usually get hair: the face (above the upper lip and

syndrome (PCOS),

on the chin), back, abdomen and iu

uhuh

•

huh

Can affect both men and women ■ ■

Hypertrichosis

Possible cause: uh

.

More problematic for hiuhi

.

Abnormal coverage of hair on areas of the body where normally only lanugo, or baby-fine hair appears

Factors that affect hair growth can be congenital, hormonal or topical, and include medical disorders and uhu

.

105 E.3

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SMARTNOTES

PAGES 42-43 In the hair, melanin is found mainly in the cortex, the hairstrand’s

NATURAL HAIR COLOR

uhiuhi

NATURAL COLORING PROCESS

uhi

.

How the natural coloring process works: Melanocytes produce melanosomes, which contain the pigment u

1.

.

Melanin is produced by melanocytes—cells that exist among the dividing cells within the hair hiuh

2.

.

Melanocytes rest near the hair bulb’s nourishment center, the dermal papilla, and form bundles of a pigment protein complex called uhi

3.

.

Genes in the human body determine the amount and type of melanin produced by the uih

.

Two types of melanin create a variety of hair colors:

Eumelanin = uhi

Pheomelanin =

/ uhi

uhi

in uhi

/uh

in uhi

The amount, size and distribution of one or both of these melanin types influence the resulting hair color. •

If the amount of pheomelanin is very concentrated and near the cuticle layer, the hair color will appear more uih

•

People with very dark, black hair may even have melanin in the uhi

uhiu

•

Lighter hair has melanin only in the

•

A total lack of pigmentation in the hair and skin results in a condition called hiui

GRAY HAIR

.

•

.

.

Caused by reduced color pigment (melanin) in the huhi uhi

of the uhiuh

.

Hair grows from the papilla with the gray color. •

Hair doesn’t turn gray after it has protruded iuhi uhi

•

the

.

Most common cause of graying hair = natural uih

uhi

105 E.3

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MATCHING Label the illustration using the terms from the Jump Start Box.

1.

ui

8.

ioj

2.

ui

9.

ijo

3.

10.

4.

u

11.

ioj

5.

oij

12.

io

6.

joi

13.

ijo

7.

oij

7 1 8 2

9

3

10

4

11

5

12 6

13

JUMP START BOX Bulge

Blood Vessels

Dermal Papilla

Arrector Pili Muscle

Outer Root Sheath

Sebaceous Gland

Hairstrand (Hair Shaft)

Hair Follicle

Hair Bulb

Inner Root Sheath

Capillary

Germinal Matrix

Sudoriferous (Sweat) Gland...