Lesson 1 Flashcards
Hair growth is a result of activity of cells found in which layer?
The basal layer
What are the three stages of hair growth?
Anagen
Catagen
Telogen
Anagen phase
Growth stage where new hairs are produced
Nutrition comes from the derma papilla
- new cells are produced in the hair follicle. Activity is greater in the hair bulb, which pulses down into the dermis and swells with cell mitosis.
Catagen phase
Regression or “falling out” stage
The hair shaft grows upward and detaches itself from the bulb & the derma papilla collapses
How long does it take for the hair to grow from the papilla to the surface of the skin?
4-13 weeks
depends on the area of the body
The quantity of hair a person has is predetermined by
Genetics
What other factor can increase body hair?
Puberty
Where does hair originate?
From hair follicles in the dermis
Most hair follicles are associated with sebaceous glands and combine to form the Pilo sebaceous unit
Hair follicle
These are pore-like indentations of the skin from which hair grows
Root
The portion of the hair which lies in the follicle
Shaft
The portion of hair which is above the surface
Bulb
The enlarged base of the root
Papilla
Contains a blood supply and other elements essential for growth of hair
Arrector pili muscle
Involuntary muscle
Attached at an angle to the base of the hair follicle
Contracts from cold or fright
Hairs stand up straight
Skin texture appears like “goose flesh”
Sebaceous gland
Found all over body except palms of hands & soles of feet
The source of new hairs
What is hair and how does it grow?
Hair is a keratinized structure pushed upward from the hair follicle
Follicles grow slanted and in different directions
Growth of hair is in the bulb (base) of the follicle
The dermal papilla is filled with nutrients and blood vessels necessary for hair growth
What is responsible for the colour of hair?
Melanocytes
These are found in the bulb
Where is the arrector pili muscle located?
Under the sebaceous gland
What does the arrector pili muscle do?
Provides thermoregulation
Strands of hair consist of three structures
Medulla
Cortex
Cuticle
The medulla
Central inner most layer of hair which is comprised of loose keratinized cells
This layer determines TEXTURE
The cortex
- This layer determines strength and colour
mass of hair
Consists of elongated keratinized cells cemented together
If the hair is pigmented, the pigment is aligned longitudinally in the cells of the cortex
The cuticle
Outermost layer
Single layer of scales which overlap like shingles
Scales are translucent and non pigmented
Confines & protects the cortex *
Gives hair elasticity *
List 3 types of hairs
Lanugo hair
Vellus hair
Terminal hair
Lanugo hair
Soft hair found on fetuses
Hair formation begins before birth and sheds after birth and is replaced with either vellus or terminal hair
Vellus hair
Hair becomes stronger and pigmented, fine, soft
Covers the whole body except palms, soles, lips, eyelids, nipples etc.
Removing this hair against the hair growth can result in follicles producing new terminal hairs therefore it is not recommended to tweeze shave or wax these fine hairs
Terminal hair
Darker, coarser hair
Found on head, brows and pubic area
How does puberty affect hair?
With hormone changes, follicles switch from producing Vellus hairs to producing terminal hairs
Lice (pediculosis capitis)
Parasitic insect that is contagious
Found in hair with egg sacs (nits) on hair shaft
Lice found on public hair “crabs”
Lice like clean hair
Dandruff (Seborrheic dermatitis)
Dry scaly material from scalp
Folliculitis
Occurs when hair follicles become inflamed
May develop any area where there’s facial hair (mens beard) or body hair
Hypertrichosis
Excessive hair growth in abnormal areas
Genetics & hormonal levels may be a factor
Hirsutism
Male pattern of hair growth in females
Strong terminal hair over the extremities
Acquired hirsutism can be secondary to endocrine disease of the pituitary, ovaries or adrenal glands
Most often is an inherited racial characteristic commonly seen in Mediterranean populations
