THE HAIR
HAIR
* NO SENSATION OR FEELING IN THE HAIR SHAFT DUE TO NERVE STIMULI * COMPOSED OF KERATIN (PROTEIN)

HAIR GROWS EVERYWHERE EXCEPT * SOLES OF FEET * PALMS OF HANDS * SOME AREAS OF GENITALS * MUCOUS MEMBRANE OF LIPS * NIPPLES (NOT INCLUDING AREOLA) * NAVAL

AREAS WITH THE HEAVIEST CONCENTRATION OF HAIR * SCALP * AXILLARY REGION * ARMS * LEGS * ON & AROUND GENITALS

*FUNCTIONS OF THE HAIR* PROTECTION * PROVIDES LITTLE PROTECTION IN HUMANS * PREVENTS THE ENTRY OF GERMS * THICK AND LONG SCALP HAIR HELP AS HEAT REGULATOR SENSORY RECEPTION
HAIR FOLLICLES ARE SURROUNDED BY SENSORY NERVES RESPOND TO PRESSURE ON THE SHAFT

FACTORS INFLUENCING HAIR GROWTH * RACE * HEREDITARY * AGE * SEX * BODY REGION * SEASON OF YEAR * HORMONES * NUTRITION * MEDICATION ( CHEMO, STEROIDS) * ILLNESS * STRESS LEVEL

THE HAIR CONT’D

HAIR ANATOMY

1.HAIR SHAFT * SUPERFICIAL PORTION * SLENDER STEM-LIKE STRUCTURE * PART OF HAIR ABOVE SCALP OR SKIN

3 PARTS OF THE HAIR SHAFT

A. CUTICLE * ARRANGED LIKE LITTLE SHINGLES ON A ROOF * OUTER LAYER * SINGLE LAYER OF OVERLAPPING SCALES * TRANSLUCENT * CUTICLE INTERLOCK TO ANCHOR THE HAIR TO FOLLICLE
FUNCTION HOLDS CORTEX TOGETHER B. CORTEX * NEXT TO THE CUTICLE * CLOSER TO CENTRE OF SHAFT * MELANIN GANULES ARE FOUND IN THIS LAYER(WHICH GIVES HAIR IT’S COLOUR) * COMPOSED OF KERATINIZED CELL, TO GIVE STRENGTH C. MEDULA * INNERMOST LAYER * CENTRE OF THE SHAFT * COMPOSED OF LOOSELY CONNECTED HORNY CELLS * MAY BE ABSENT IN VERY FINE HAIR OR EVEN WITHIN THE LENGTH OF SOME HAIR

2.SEBACEOUS GLAND (OIL GLAND) * 2 OR MORE ATTACHED TO EACH HAIR COATING HAIR WITH SEBUM
SEBUM FUNCTIONS: * LUBRICATES HAIR * PROTECTS HAIR * KEEPS HAIR SOFT & PLIANT * KEEPS SKIN SOFT & SUPPLE * PREVENTS EXCESS ABSORPTION * PREVENTS EXCESS EVAPORATION * LESSONS HEAT LOSS * MAINTAINS PH * INHIBIT GROWTH OF BACTERIA

THE HAIR CONT’D

3.HAIR FOLLICLE * DEPRESSION IN THE SKIN CONTAINING THE HAIR ROOT

TWO LAYERS: A. OUTER ROOT SHEATH * ALLOWS RENEWAL DEVELOPMENT OF THE HAIR CELLS TO TAKE PLACE * DOWNWARD CONTINUATION OF EPIDERMIS

B. INNER ROOT SHEATH
- CELLS INTERLINK WITH HAIR CELLS HELPING TO SECURE HAIR WITHIN FOLLICLE

4. GERMINAL MATRIX - LIVING & REPRODUCING PART OF BOTH HAIR & NAILS - ALSO KNOWN AS “THE HAIR MATRIX”

5. HAIR PAPILLA - SMALL CONE SHAPED ELEVATION AT THE BOTTOM OF THE HAIR FOLLICLE - HOUSES BLOOD SUPPLY - NOURISHMENT FOR THE MATRIX - NUTRIENTS FROM GI TRACT & RESPIRATORY SYSTEM FEEDS THE CELL FOR GROWTH & DEVELOPMENT - HORMONES FROM THE ENDOCRINE SYSTEM DETERMINES PATTERN OF HAIR GROWTH

6. HAIR ROOT -DEEP TO THE SURFACE THAT PENETRATES TO DERMIS -CONTAINS MATRIX -CELLS IN THE MATRIX REPRODUCE NEW CELLS BY MITOSIS

7. HAIR BULB -INFERIOR & SWOLLEN PART OF THE ROOT -LOCATED AT THE BASE OF HAIR FOLLICLE WHERE NEW HAIR DEVELOPS

8. ARRECTOR PILI (PLURAL)
-INVOLUNTARY MUSCLE FIBRE IN THE SKIN ATTACHES TO BASE OF HAIR FOLLICLE
-COLD OR FRIGHT CAUSES CONTRACTION OF THE MUSCLE WHICH PULLS THE HAIR BULB UPRIGHT AND CREATES GOOSE BUMPS

9. NERVE ENDINGS -SENSORY NERVE ENDINGS FROM A SINGLE NERVE ENCIRCLES FOLLICLE -IF HAIR IS TOUCHED IT SENDS SIGNAL TO THE BRAIN (SENSITIVE TO TOUCH) THE HAIR CONT’D
HAIR GROWTH -DEVELOPS MANY MONTHS BEFORE BIRTH -EPIDERMIS GROWS DOWN INTO DERMIS, FORMING THE FOLLICLE
-BASAL CELL DEVELOPS INTO INNERMOST LAYER OF THE FOLLICLE, INNER ROOT, AND FORMS AT THE BOTTOM A CLUSTER OF CELLS CALLED GERMINAL MATRIX
-HAIR PAPILLA PROTRUDES INTO GERMINAL MATRIX TO SUPPLY NOURISHMENT
-GERMINAL MATRIX ARE RESPONSIBLE FOR FORMING NEW HAIR BY UNDERGOING MITOSIS WHICH PUSHES THE SHAFT UPWARDS AND BECOMES KERATINIZED TO FORM HAIR
-PUBERTY CHANGES HAIR GROWTH IN TEENAGERS
-PREGNANCY CAN ACTIVATE HAIR GROWTH MAKING HAIR THICKER IN CERTAIN AREAS OF THE BODY (ABDOMEN)
-MENOPAUSE CAN ACTIVATE MALE CHARACTERISTIC HAIR GROWTH (EXCESS FACIAL HAIR)

NATURAL HAIR COLOUR -COLOUR DEPENDS ON MELANIN, PRODUCED BY MELANOCYTES -MOST HAIR PIGMENT IS IN THE CORTEX -AMOUNT OF MELANIN IS GENETICALLY DETERMINED -PIGMENT DISAPPEARS, HAIR LOOKS GREY OR WHITE -LARGE AMOUNTS OF MELANIN MAKE HAIR DARK BROWN OR BLACK -SMALLER DEPOSITS MAKE HAIR BROWN, SANDY, AND BLONDE -RED HAIR IS THE PRODUCT OF A SEPARATE GENE. THIS GENE PRODUCES RED
PIGMENT TO ADD TO ANOTHER COLOUR
-DARK HAIR HIDES RED, LIGHT HAIR RESULTS IN STRAWBERRY BLONDE
-TRUE REDHEADS POSSESS ONLY SPECIAL RED PIGMENT
-MELANIN PROTECTS HAIR FROM SUNLIGHT