Presentation on theme: "Hair Structure & Growth"— Presentation transcript:
1 Hair Structure & Growth hair growthhair life cycle
2 Basic Hair StructureThis diagram shows the three layers of a hair follicle, the cuticle, cortex and medulla.The cuticle is made up of scales and istranslucent (the hair colour shows through it).It has a protective function.The cortex forms the bulk of the hair andit is in this part of the hair that the chemical changes of perming and neutralising take place.The medulla is an air space in the middleof the hair and may not always be present .
3 Hair Growth There are two main type of hair on the human body; Fine vellus hair which grows on the body.Stronger terminal hair which grows on the scalpand makes up eyebrows, eyelashes, beards and moustaches.However there is a third type of hair, lanugo hair, it is only found onhuman foetuses and is even finer than vellus hair.
4 Hair Growth The scalp ( and skin) is divided into two layers: The outer layer – the epidermis –is the outer protective layer of skin.It is constantly shedding itself,losing dead skin cells. When this happens excessively on the scalp it is knownas dandruff.epidermisThe inner layer – the dermis –is the thickest and mostimportant part of the skin.It is where you will find;dermishair folliclessebaceous glanderector pili musclesweat glandsblood supplyDermal papilla
5 Hair GrowthHair is made of the protein keratin, all proteins are made up of amino acids.The hair you see emerging from the scalp is dead, it does not hurt when we cutthrough it, or when chemicals such as perm lotions or bleaches are put onto it.But at the base of the follicle the hair is alive and growing, that is why we canfeel someone pulling our hair because it is attached to the scalp by its roots,sitting in tiny pockets called the hair follicle.The sebaceous gland is also attached to thehair follicle and produces sebum, the hair’snatural oil. The sebum flows around the hairroot and outwards onto the scalp surface.If too much sebum is produced, the scalpand hair will be too greasy, but if too littlesebum is produced the hair and scalpwill be too dry.The erector pili muscle isattached to the hair root andcontracts to pull the hair upright,creating the goose pimpThe heart pumps blood containing food and oxygen ( needed to make new keratin)through our arteries towards the skin surface. The arteries become small blood capillariesin the dermis, where they supply into the bottom of the hair root or follicle to feed the dermal papilla.The more blood flowing towards the hair papilla, the more the hair will grow.
6 hair life growth cycleHair growth needs energy to grow. The papilla oxidation of glucose provides that energy. The blood in turn supplies oxygen and glucose to the papilla. Hair grows from the bottom of its root at the dermal papilla, where new cells are constantly being produced. These soft cells become hardened to form strong hair above the skin surface. The average rate of hair growth is 1.25 cm.The growing stage of the hair is called the anagen stage. When the hair starts to go into its resting stage, it is said to be in the catgen stage. The resting stage is called the telogen stageAnagenActive growth 1-7 years(average 3 years)The only way to improve the conditionof the hair permanently is throughthe blood supply to the papillaCatagenBreakdownAnd change2 weeksTelogenResting Stage3-4 monthsAnagen RegrowthThe thickness, shape and texture of the hair is determine at this stage