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What is hair made of?

The structure of hair

Did you know? We have on average between 80,000 to 150,000 hairs on our scalp1. It varies from person to person depending on their lifestyle and genetic make-up2. To have beautiful hair, you need to understand the structure of your hair. 

Hair is made up of 3 main parts:

1)   The hair shaft3

This is the visible part of the hair you can see on your head. It is made up of dead cells, which is why it doesn’t hurt to have a haircut.

The hair shaft itself consists of three layers4:

The medulla

The central section of the shaft.

The cortex

The thickest part of the shaft. It contains keratin, the protein that gives the hair its structure and strength. It also generates melanin, the pigment that gives your hair its colour.

The cuticule

The protective part of the hair that surrounds the cortex. For glossy hair, the scales of the hair cuticle must be closed.

2)   The hair follicle

This anchors each hair into the scalp and is the living part of your hair. If it is curved or oval in shape, the hair that grows from it will be curly. If it is round, the hair will be straight.

3)   The hair bulb

This is the base of the hair follicle and is made up of living cells called keratinocytes. The blood vessels in the capillary papilla nourish these cells and supply hormones and other elements that affect the growth and structure of the hair at different times of life. Hair receives oxygen and various nutrients from these blood vessels to keep it healthy.

Krause, K.; Foitzik, K. Biology of the Hair Follicle: The Basics. Semin. Cutan. Med. Surg. (2006)
Paus, R. & Cotsarelis, G. The Biology of Hair Follicles. N. Engl. J. Med. (1999)
Hoffman, M. M. Hair (Human Anatomy): Image, Parts, Follicle, Growth, Problems, and More. (2019)
Araújo, R.; Fernandes, M.; Cavaco-Paulo, A.; Gomes, A. Biology of Human Hair: Know Your Hair to Control It. (2010)