Hair is a filament made mostly from protein (keratin) and protrudes out through epidermis. Thick, long hair on head is terminal and fine hairs throughout body are called velus hairs.
Hair consists of two parts: Hair shaft and Hair root
1. Hair shaft:
It extends above the skin surface and consists of:
Cuticle: outermost layer formed from dead cells and gives the hair shaft strength.
2. Hair root:
Cortex: Fibrous middle layer of hair giving hair its weight and producing melanin.
Medulla: inner most layers consisting of circular cells.
It is part of hair below the skins surface and consists of:
Follicles: Cell division and hair growth begins here.
Hair bulb: Cells of hair shaft are produced here.
Erector pili: makes hair stand straight up when scared or cold.
Sebaceous gland: Secretes sebum that lubricates hair.