Lesson Aims List the different parts of the hair Explain how hair grows Differentiate between different types of hair

Hair Function Grows all over the body except soles of feet and palms of hand Protection – eye lashes, eye brows, nose and ear hair Body hair keeps us warm and protects against sunlight Protects against friction

Hair Structure Made from protein called KERATIN Dead structure Hair divided into 3 different parts: - Hair shaft - Hair root - Hair bulb

Hair Shaft Visible part showing above the skin Protects against sunlight, dust, sweat dripping into eyes Keeps you warm

Hair Root Found under the skin Not visible Surrounded by a Root sheath At the bottom of the root is the bulb

Hair Bulb Found at the base of the hair root Bulb is where cells grow and mitosis happens Mitosis – cell division

Hair Root Sheath Found surrounding the hair root Inner and outer root sheath Outer sheath forms follicle wall Cells constantly dividing Allows follicle to renew cells throughout life cycle Inner sheath responsible for anchoring the hair Important for shaping the hair Important for making the hair smooth

A small tubular cavity containing the bulb of the hair Hair Follicle A small tubular cavity containing the bulb of the hair

Dermal Papilla Found within the hair bulb Connective tissue Contains blood vessels Provides blood to help hair grow

Hair Matrix Surround the dermal papilla Contains the cells that divide and create the hair shaft and root

Hair Bulge Located in the outer root sheath at the insertion point of the arrector pili muscle It has several types of stem cells, which supply the entire hair follicle with new cells, and take part in healing the epidermis after a wound

Layers of Hair

There are three stages to hair growth: Anagen Catagen Telogen

Hair Growth: Anagen Active growing stage Lasts few months to several years Hair germ cells reproduce at matrix New follicle is produced Extends in depth and width Hair cells pass upwards Form hair bulb Cells keep rising up follicle, pass through bulb and form structure of the hair Inner root sheath grows with hair and anchors

Hair Growth

Catagen Phase between the active and resting phase Lasts two to four weeks Hair separates from dermal papilla and moves slowly up the follicle Follicle begins to shrink Inner root sheath dissolves and hair can be brushed out

Telogen Resting phase Hair is shed on the skins surface New replacement hair begins

There are 2 main types of hair Vellus hair Terminal hair

Vellus Soft, downy unpigmented hair Found over most of the body except soles of feet, palms of hand, lips and genitals When stimulated by puberty, vellus hair can grow into terminal hair

Terminal Longer, darker, coarser hair Found on scalp, under arms, eyebrows, pubic regions Adult hair growth