INTRODUCTION – HAIR
Hair – Anatomy
– Partially live and partially dead, belongs to integumentary sy
– Follicle part (root) live and shaft part dead
STRUCTURE OF HAIR
Skin
– 7 layers – 2 dermal layers, 5 epidermal layers
– Dermis – 2 layers – Reticular and Columnar layers
– Extension of dermis – follicle, Extension of Epidermis – hair shaft
DESCRIPTION OF THE LAYERS
- Reticular dermis – Rich in blood vessels
- Columnar dermis – Filled with cells, extra – cellular matrix, gluten
- Follicle – root of the hair – contains hair matrix, dermal papilla
- Dermal papilla – seat of the follicle, connectivity between the hair follicle and shaft, presence of androgen receptors
- Hair matrix – contains stem cells, keratinocytes and melanocytes
- Stem cells – mother cells producing new undifferentiated cells
- Keratinocytes – normal cells – contains melanin pigment and other nutrients and forms as a shaft
- Melanocytes – produces melanin pigment
- Interstitial spaces – present in between dermal papilla through which the cells squeeze out to form shaft
- Arrector pilli muscle – supports the hair shaft and keeps the hair erect
- Sebaceous gland – secretes sebum, regulates body temperature, lubricates and avoids friction
PARTS OF SHAFT
- Cuticle – Outermost, Discontinuous, transparent layer
- Cortex – Contains keratinocytes
- Medulla – Functionally not significance not defined
PHYSIOLOGY/ FUNCTIONS OF HAIR:
- Protective
- Excretory
- Beauty
CYCLES/ PHASES OF HAIR GROWTH:
- ANAGEN – GROWTH PHASE
- CATEGEN – INTERMEDIATE PHASE
- TELOGEN – RESTING PHASE
- RE- ANAGEN – REGROWTH PHASE
TYPES OF HAIRS
- VELLUS HAIRS:
- Lifeless Hair
- Elasticity of Arrector Pilli is lost
- Colorless
- Forms as question mark
- Tends to fall hair
- Strength less hair
- Latin – Vellus -“a fleece” or “wool”
- INTERMEDIATE HAIRS:
- Phase of conversion of vellus hair into terminal or vise versa
- TERMINAL HAIRS:
- Good hair
- Strengthened hair
Regarding Hair disorders and remedies – please wait for the next post 🙂
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