Hair shaft

Hair Shaft

The hair shaft is the part of the hair that is visible above the skin. It is made up of a protein called keratin and is produced in the hair follicle, a small organ in the skin that produces hair. The hair shaft is made up of three layers: the cuticle, the cortex, and the medulla.

Structure

The hair shaft is composed of three layers:

• The Cuticle is the outermost layer. It is made up of flat, overlapping cells that protect the inner layers of the hair shaft.

• The Cortex is the middle layer. It makes up the majority of the hair shaft and contains the hair's pigment, which gives the hair its color.

• The Medulla is the innermost layer. It is not always present, especially in fine or light-colored hair.

Function

The hair shaft has several functions:

• It helps to protect the skin from ultraviolet radiation.
• It helps to regulate body temperature by providing insulation.
• It plays a role in sensory perception, as it is connected to nerve endings in the skin.

Health and Disorders

There are several disorders that can affect the hair shaft:

• Trichorrhexis nodosa is a condition in which the hair shaft becomes weak and breaks easily.
• Monilethrix is a condition characterized by beaded or moniliform hair shafts.
• Pili annulati is a condition in which the hair shaft has alternating light and dark bands.

See Also

• Hair follicle
• Hair growth
• Hair disorders

References

Hair shaft Resources
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