Level 2 A&P Hair.pptx

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• Beauty
• Further Education (Key Stage 5)

- Hair

A&P Theory

Hair -Normal structure of the hair, composition, properties and adverse conditions and disorders.

• Describe the structure and function of the hair

• Describe the structure and growth cycle of the hair

• Describe diseases and disorders of the skin and hair

Functions of hair

• The main function of the hair is protection.

• Hair covers the head to keep it warm, protect it from injury, and overexposure to the sun.

• Eyelashes and eyebrows shield the eyes. They prevent objects from entering the eyes and catch perspiration.

• Provides a larger surface area for sweat to evaporate from to cool the body.

• When we are cold the arrector pili muscle, which is attached to the hair follicle, pulls the hair shaft up to trap air against the body.

• Tiny hairs in the ears and nostrils, called cilia, catch and filter out dust particles to prevent them entering the body.

Structure of the hair shaft

The hair shaft is the part of the hair that is visible above the skin. The part embedded in the skin is called the root. The hair shaft is made up of three layers of keratinised cells:

Structure of the hair shaft

Structure of the hair shaft

Structure of the hair shaft

The Hair Growth Cycle

The hair follicle has three stages of growth:

• These stages include periods of activity and rest.

• They vary from person to person.

• The growth rate varies in different parts of the body.

• The hair on the head has a growth cycle of around 2-8 years while the growth rate of eyelashes is about 4 months.

The three stages of hair growth cycle are:

1. Anagen

   1. Catagen

   2. Telogen

anagen: the hair is actively growing

catagen: the stage where changes occur

telogen: the stage where the follicle ‘rests’ and no hair is growing.

The hair growth cycle

Structure of the hair follicle:

• The hair follicle is a complex structure that produces hair. It extends deep into the dermis.

Dermal Papilla:

• It provides a constant supply of blood, oxygen and nutrients to the hair root. It is also involved in transporting protein cells to the growth site where new hair is produced.

Capillary Loop:

• At the base of the hair follicle is a mass of loose connective tissue which contains minute capillaries to nourish all the cells of the follicle.

Hair Bulb:

• This is the part of the hair at the base of the hair root.

• It includes the germinal matrix and the dermal papilla.

• The cells in this structure divide and grow to build the hair shaft.

Hair types

There are 3 hair types:

1. Lanugo

2. Vellus

3. Terminal

Lanugo hair

• Lanugo hair is very soft fine hair that covers a baby in the womb and disappears a few months after birth.

Vellus hair

• This is the soft fine downy hair which is found all over the body with the exception of the soles of the feet and palms of the hands. It usually lacks any pigmentation. This hair has shallow roots.

Terminal hair

• At birth, this type of hair is found on the scalp, eyelashes and eyebrows. During puberty it grows under the arms and in the groin areas. During male puberty it also grows on the lower legs and chest and as a beard. This type of hair has a well-developed root and bulb with a strong blood supply. The follicle extends deep into the dermis during anagen growth.