Hair

Question 1

Pilo-Sebaceous Unit

Answer 1

This contains the hair shaft the protrudes from the follicle opening

The follicle is a down growth of the epidermis, it lies at an angle, the erector pili muscle is attached to the follicle bulge

The sebaceous glands are attached and open into the hair follicle

The sebaceous gland produces the oil sebum, which lubricates and waterproofs the hair and skin

Question 2

The Cuticle

Answer 2

Outer coating of the hair which offers protection

Consists of overlapping flattened keratinised cells, working down from roots towards tapered end of hair.

These scales interlock to the inner root sheath ensuring the hair shaft is fixed firmly to the follicle

The cuticle vary from 7-10 layers of scales and contains no pigment

Question 3

The Cortex

Answer 3

Most important makes up 75-90% of hair in bulk

Contains colour pigments, brown/black, yellow, red or white

Elastic and is made up of macro and micro fibrils and keratin. Cross bonds of hydrogen and Di-sulphide linkages

Question 4

The Medulla

Answer 4

Centre of the hair, made from soft keratin cells and stacked interspersed with air spaces

Affects tone and sheen of the hair and may be continuous, fragmented or completely absent vellum hairs do not have medulla

Question 5

Catagen

Answer 5

Mitosis ceases and degeneration of this follicle wall. The dermal papilla separates from the matrix now known as a club hair, begins to lose its attachment and move towards the surface. Nourishment is no longer received via dermal papilla but from the follicle wall. Duration is between 2-3 weeks

Question 6

Telogen

Answer 6

The follicle rests, remaining dormant until reactivated by hormonal influences. Telogen may last for a few weeks to a few months depending on the type and location of hair. The telogen hair has lost all contact with the surrounding tissue and will be either shed or brushed away by a new hair when hair follicle returns

Question 7

Anagen

Answer 7

The dermal cord proceeds downwards growing in width and depth due to mitotic activity. This down growth continues until the follicle is approx six times longer than in telogen stage. The dermal cord envelopes the dermal papilla. Increases mitotic activity of the germinal matrix initiates the production of the hair and inner root sheath. Keratinisation occurs in the upper bulb, duration is between 2-7 years