The hair has an elongated structure and consists of keratin proteins. These proteins are also the main constituents of nails and are very resistant to mechanical influences. As all proteins in the body, they are composed of long chains of amino acids.
The diameter of the hair varies from person to person, but is usually between 0.05 in 0.1 mm.
The epidermis creates small sockets that we call hair follicles, which contain the root of the hair.
The follicle is a structure, from which the hair grows. It is located about 5-10 mm under the skin surface, in the fat tissue. The bottom part of the follicle is called a hair bulb. It consists of cells that divide and grow and produce elongated hair fibres. Next to them pigment cells are located (melanocytes), which give colour to the hair. Cells in the hair bulb contain receptors for male sex hormones.
In the basis of every bulb there is a hair papilla, which contains vessels. It is necessary for the nourishment of the growing hair.
Other structures, located in the follicle, are the sebaceous glands, which produce natural oils for greasing the hair and skin.
The part of the hair above the skin surface is called the hair shaft. It contains keratinized dead cells, binders and smaller amounts of water.
The hair constitutes of three layers. Inner layer (medulla) only exists in thick hair. Middle layer (cortex) constitutes of keratin fibres. They give the hair strength and colour. The outer layer is called the cuticle; its function is to protect the cortex.