Hair Structure and Growth Cycle PDF

Hair structure and growth cycle  Hair is found all over the body except on the palm of the hand, the soles of the feet, lips and external genitalia. Types of There are 3 different classifications: hair o Lanugo o Vellus o Ter...

Hair structure and growth cycle  Hair is found all over the body except on the palm of the hand, the soles of the feet, lips and external genitalia. Types of There are 3 different classifications: hair o Lanugo o Vellus o Terminal Lanugo  Starts growing when you’re still in the womb and is the first result of cellular activity in the skin.  Falls out either just before or just after birth and are replaced by slightly coarser hair. Vellus  Is the soft downy hair often found on the cheeks and all over body.  Usually lack pigmentation and grow form a shallow depth at about sebaceous gland level.  Rarely grows longer then 2cm in length and are usually straight due to the fact that they have shallow follicles.  Do not become terminal unless stimulated by a topical (i.e. shaving or plucking) or systemic (i.e. hormones or medication) cause. Terminal  Are pigmented, deep seated, coarse hair, which have a well-developed root and bulb and often extent into the subcutaneous layer.  Found on the scalp, eyebrows, eyelashes, pubic & underarm areas, legs, face and chest for males.  Is comprised of 3 layers: The cuticle, cortex and medulla. Layers of the hair Cuticle Is the outer layer of scale like cells with each overlapping another. Contains no pigment, is translucent and allows colour from beneath to show through. The cuticle protects the hair. Cortex Is the main part of the hair and contains elongated cells, which are keratinised and cemented together. The pigment granules ( eumelanin for black/brown or pheomelanin for red/yellow) are present in this layer. The strength, thickness and elasticity of the hair is determined by how the cells are held together in the cortexBulb Is the large base at the bottom of the root and encases the dermal papilla. The matrix is the lower region of the bulb where the cells divide rapidly to produce the new hair and follicle structure. Medulla Is the middle, soft, sponge core of the hair. This layer contains large, loosely connected, keratinised cells, which may or may not be continuous. This result in air space, which determine the sheen and colour tones by influencing the reflection of light. The medulla is often not present in fine terminal and vellus hair. Structure of the hair and its follicle  Hairs are dead structures made of a hardened protein called keratin.  Keratin provides the body with a protective toughness for its entire surface.  The hair is comprised of 3 different areas: 1. The shaft 2. The root 3. The bulb Shaft Lies about the skin surface, but also runs through the centre of the hair. Root Lies underneath the skin, inside the follicle. Bulb Is the large base at the bottom of the root and encases the dermal papilla. The matrix is the lower region of the bulb where the cells divide rapidly to produce the new hair and follicle structure. Dermal Papilla Is a loose mass of connective tissue surrounded by the hair bulb. It has excellent blood supply, providing food and oxygen which is essential for hair growth. The dermal papilla is a separate organ that serves the follicle but is not part of the hair. It is supplied by nutrients from the capillary loop. Follicle structure  The hair follicle is an indentation of the epidermis with the wall of the follicle being formed from a continuation of the cellular layer of the skin’s surface.  The follicle has 3 sheaths:  Inner root sheath  Outer root sheath  Connective tissue sheath Inner root sheath  This layer is closest to the hair and has scale like cells that interlock with the cuticle to hold the hair firmly in place.  The hair and the inner root sheath grow upwards, together.  The inner root sheath is made up of three layers – Cuticle, Henle’s layer and Huxley’s layer. Outer root Sheath  This is the follicle wall, it does not grow upwards but remains stationary in one place. Connective tissue sheath  This surrounds the rest of the follicle and the sebaceous gland.  This is an extension of the papillary layer of the dermis and provides a sensory nerve and blood supply.   All hairs grow in cycles that occur at various speeds all over the body.  All hairs will progress through this cycle and then fall out making way for new hairs Hair to grow. growth  The speed at which the hair re-grow will depend on the stage of growth the hair cycle  was removed. For waxing/sugaring purposes, it is most beneficial if a hair is removed in the anagen stage of growth, as it takes much longer to re-grow.  There are 3 stages in the hair growth cycle and these are known as:  Anagen – Active  Catagen – Changing  Telogen – Tired (resting) Hair The hair growth cycle is repeated continuously growth as long as there is nourishment available. cycle If the hair follicle is damaged in any way such as with epilation, illness or old age the hair will not re-grow or will re-grow finer. Hair does become thinner with old age due to the hormonal changes in the body.  Anagen  Active phase - receive nourishment in the form of food and oxygen from the blood supply via the dermal papilla.  Hair cells divide in the matrix to produce new hair.  Hair grows upwards and outwards and eventually out of the skin’s surface. Catagen  Changing phase sometimes referred to as transitional stage.  During this stage, the dermal papilla separates from the hair but the hair still receives a small amount of nourishment for the follicle walls.  Hair gradually becomes drier and continues to move upwards, to just below the sebaceous gland, where it can easily fall out. Telogen  Tired/Resting phases – the dead hair lies in the follicle waiting to fall out or for new hair to push it out.  Hair receives no nourishment.  Follicle rest until it is stimulated by hormones to return to the anagen stage. How would you recognise an anagen hair?  A terminal hair removed in this stage of growth will have a dark bulb and the inner root sheath – which appears as a clear jelly like coating. How would you recognise a catagen hair?  A hair removed in this stage of growth will appear limp with a slightly straggly end. How would you recognise a telogen hair?  A hair removed in this stage of growth will have a straggly brush like end, referred to as club-ended. Hair re-growth  It is important to explain the basic principles of the hair growth cycle to clients so they understand how the hairs re-grow and replace themselves.  Hair will be in different stages of growth so when removed it will grow back at different stages.  Most hair takes approximately 16 weeks to regrow, however when carrying out waxing/sugaring treatment you will not remove all the hairs.  This is due to some hair being in the early anagen stages of growth (still underneath the skin surface) and cannot be removed.  It is these hair that will become visible within a few weeks after the waxing treatment, not the hairs that were removed.  With continuous regular waxing treatment, you will notice that the hairs are forced into a similar hair growth cycle, and therefore your client will remain hair free for lightly longer. Factors affecting hair growth  Hormones  Seasons  Age  Race/origin  Colour  Stress  Medication  Health and diet  Medical conditions  Hereditary  Part of the body