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 🙂