Hair

Hair is a protein filament that consists of alpha keratin. It grows from hair follicles present in the dermis of the skin. Hair is a skin appendage, and it's a characteristic feature in humans. It has two parts; the root and the shaft. The root is deep inside its follicle under the skin. The shaft is the part that is seen above the skin. Hair grows on areas of the skin that are not glabrous like palms, soles and mucous membranes. About 5 million hairs are found throughout the body of an adult human. The number declines with age. Scalp has the highest density of hair follicles. Embryologically, the hair follicle is formed around 10th week. There are 3 types of hair; lanugo, vellus, and terminal. Lanugo grows in fetalhood. Vellus in childhood. And terminal in adulthood. From inside out, the layers of the hair shaft are the medulla, cortex and cuticle. Normal hair has 4 phases; anagen (active, growing phase), telogen (passive, resting phase), catagen (regression phase) and exogen (shedding phase). Hair has a lifespan of 3-11years. There’s an abrupt growth of hair in parts of the body during puberty due to the effects of sex hormones- the androgens and estrogen. Hair is that structure in the body that over the years we’ve paid less attention to in terms of understanding the whole functions, but focused more on the cosmetic importance. Men and women make different hairstyles to look more beautiful. That's good. But interestingly, hair has got other important functions like protection, regulation, sensation, psychology, and socio-cultural purposes. Happy weekend.