Structure and Function of Hair

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Over entire body except palms, soles, glans penis, vulval introitus

Three types of hairs:
Lanugo – fine hairs – formed in foetus – normally shed before birth
Vellus – short, fine, light, fine – cover most body surfaces
Terminal – longer, thicker, darker – on scalp, eyebrows, eyelashes, pubic, axillary and beard

Structure of hair shaft:
Outer cuticle – encloses cortex of packed keratinocytes.
3 concentric layers:
1) Cuticle – outermost; single layer of overlapping cells; most highly keratinised layer of hair shaft
2) Medulla – central core; absent in fine hair; cells partially seperated by air cells

Structure of hair follicle:

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