Structure of hair

Hair and its structure

The structure of hair consist two parts. One is visible part called as shaft and the other is the root called as follicle.

Hair Shaft:

The outer visible part, hair shaft has three layers.

Hair shaft and its layers

                     Hair shaft layers

1. Medulla:

  • It is the innermost layer of the hair surrounded by cortex.
  • This is the thinnest layer of the hair shaft.
  • This is found in hair with big diameter and is not found in all types of hair.
  • The role of medulla in hair is not yet clear to the scientists.

2. Cortex:

  • This is the main layer or part of the hair as it defines hair colour and hair texture.
  • This is the thickest layer of the hair.
  • It contains Melanin and Pheomelanin which define the colour of the hair.
  • It contains keratin, a protein that is comprised of amino acid units. Keratin is responsible for shaft growth.

3. Cuticle:

  • This is the outermost part of the hair shaft.
  • It comprises of overlapped dead cells forming scales of about 10 layers. Depending on the density of these folded scales, the hair looks healthy and shiny.
  • If the scales are unfolded and broken the hair looks rough and lifeless.
  • The scales are colorless, so the layer is transparent which allows the color visible from the inner layer, cortex.

Hair Follicle:

Hair follicle is the part of the hair which is not visible outside and the hair shaft arises from here.

Hair follicle has three segments. They are:

  • Infundibulum
  • Isthmus
  • Inferior

Papilla is one more important part of the hair present in the hair follicle, which is responsible for providing nutrients to the growth of the hair.  click here for more knowledge on hair follicle.

Dermal papilla:

Hair structure with dermal papilla

                          Hair structure

  • It provides oxygen and nutrients to the hair follicle in the scalp.
  • Papilla is connected to the hair bulb present at the bottom of the follicle. So, that the hair can receive the oxygen and nutrients from the blood through this papilla.
  • If the papilla is not connected to the hair bulb, the hair growth is impossible and hair follicle is useless.
  • ATP is the bio-organic process in which oxygen from blood is converted to usable energy.

 

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