Hair Structure - Introduction

Hair Structure - A guide to Hair Loss

Our hair is a fascinating structure which is comprised of follicles, sebaceous glands and strands. Hair growth follows a normal cycle in much the same way as other processes in the body, and this is consistent throughout our lifetime.

What is ‘hair’?

We think of our hair as a collection of strands which grow from the scalp. This is largely correct as hair does grow under the skin which then follows a hair growth cycle which is repeated over and over again, unless it is interrupted by illness, genetic or external factors.
Hair is comprised of two parts:

• Follicle
• Shaft

Follicle

Hair grows from follicles which are small, cup-like structures underneath the skin. They contain blood vessels which transport oxygen to encourage hair growth. Each follicle contains a ‘bulb’ which is formed by cells within the body and this produces those long fibres of hair. It also produces a pigment called melanin which is responsible for the colour of our hair.

Plus the cells within this bulb contain receptors for the male hormones or androgens. This is an important factor in male pattern baldness.

Each follicle is covered by internal and external root sheaths which are located underneath the skin. Muscle fibres are also connected to the base of each follicle which cause the hair strands to grow at an angle.
At the base of these follicles lie the sebaceous glands. These glands produce natural oil called sebum which lubricates the hair strand. These glands are found almost everywhere on the skin except for the soles of the feet and the palms of the hands.

The thickness of your hair is determined by how many sebaceous glands you have. The greater the number of these glands the thicker your hair.

Shaft

The shaft protrudes through the skin, and is the part of the hair that we see. Each shaft is composed of a series of proteins called keratins and a small amount of water which help to bind these together.

This material is also found in your finger and toenails.
Each hair strand is comprised of 3 layers:

• Cuticle (outer layer)
• Cortex (middle layer)
• Medulla (inner layer)

The cuticle is a thin, colourless layer which helps protect the inner and middle layers of the hair strand. It is the layer which is most likely to be damaged by sun exposure, hairdressing treatments and pollution.

The cortex is composed of keratin (protein) fibres and gives our hair its texture, colour and strength.
The medulla is the innermost layer of the hair strand but is only found in large, thick hairs.

Your hair goes through a regular cycle of growth and shedding which carries on throughout your life. However, this can be disrupted by genetic reasons, accident or illness, pollution, stress and other internal/external factors.

Source :  http://www.medic8.com/healthguide/hair-loss/hair-structure/index.html

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