Cortex (hair)

Cortex (hair)

The cortex is the thickest layer of the hair and contains the majority of the hair's pigment. This pigment gives the hair its color. The cortex, which contains the hair's melanin, is primarily responsible for hair color, as the other parts of the hair, the cuticle and the medulla, do not contain any pigment.

Structure

The cortex of the hair is located between the hair cuticle and medulla and is the largest part of the hair shaft. The cortex is composed of keratin fibers that are tightly packed together and contain pigments. These pigments, known as melanin, are responsible for the color of the hair. The type and distribution of melanin in the cortex determine the color and intensity of the hair color.

Function

The primary function of the cortex is to provide strength, elasticity, and texture to the hair shaft. The cortex achieves this through the keratin fibers and the hydrogen bonds that hold them together. These bonds can be temporarily broken by water and heat, allowing the hair to be styled. Once the hair dries or cools, the bonds reform, and the style is set.

Hair color

The color of hair is primarily determined by the distribution and type of melanin within the cortex. There are two types of melanin found in the hair: eumelanin, which is brown or black, and pheomelanin, which is yellow or red. The combination and concentration of these pigments determine the hair's color.

Hair damage

Damage to the cortex can result in hair breakage, split ends, and frizz. This damage can be caused by heat styling, chemical treatments, and environmental factors such as sun exposure. Once the cortex is damaged, it cannot be repaired, and the hair must be cut to remove the damaged portion.

See also

• Hair follicle
• Hair care
• Hair coloring

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  Diagram of a hair shaft

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  Anatomical illustration from Gray's Anatomy