JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Pharmacy III COSMETIC SCIENCE Previous Question Paper (September-2021 - R17)

Hair is a complex, keratinized filament that originates from the hair follicle in the dermis. It consists of two main parts: the hair follicle (root) and the hair shaft (the visible part).

The structure of the hair shaft is composed of three concentric layers:

1. Medulla: The innermost core, which may be absent in fine hair. It consists of loosely arranged cells and air spaces.
2. Cortex: The middle and thickest layer, containing keratin filaments, pigments (melanin) that provide hair color, and structural proteins that determine hair strength and elasticity.
3. Cuticle: The protective outer layer consisting of overlapping, transparent, scale-like cells that protect the inner layers from environmental damage.

Hair functions include protection (e.g., scalp hair protects against UV radiation), thermoregulation, sensory perception through follicle nerve endings, and social/aesthetic communication.

The hair growth cycle is a continuous process consisting of three distinct phases:

1. Anagen (Growth Phase): The active phase where cells in the hair bulb divide rapidly, resulting in hair shaft formation. This phase lasts 2 to 7 years.
2. Catagen (Transition Phase): A short, 2 to 3-week phase where hair growth stops, the follicle shrinks, and the hair detaches from the dermal papilla to form a club hair.
3. Telogen (Resting Phase): The final phase lasting about 3 months, during which the hair remains in the follicle until it is shed and a new anagen hair begins to grow, pushing the old hair out.