Chapter 11 Properties off the Hair & Scalp

Chapter 11 The hair is part of the body and , like every other part, must be cared for and nourished. Just as you replenish body fluids after extended exercising or illness, you must also replenish the needed nutrients for healthy hair. With all the styling tools and chemicals used on the hair today, it is constantly at risk of damage. It is essential that, as a hairdresser, you fully understand the importance of caring for the hair and scalp.

Structure of the Hair Shaft The three main layers of the hair shaft: cuticle cortex medulla

Hair Shaft Cuticle outermost layer of hair consists of a single, overlapping layer of transparent, scale-like cells like a roof shingles hair’s primary defense against damage each individual cuticle is attached to the cortex imbrications allows liquids to penetrate

Hair Shaft Cortex Middle layer of hair Fibrous protein core formed by elongated cells containing melanin pigment 90% of hair weight Hair elasticity Changes resulting from chemical services occur in the cortex

Hair Shaft Medulla Innermost layer Referred to as the pith of the hair Composed of round cells Very fine & naturally blonde hair may not even have a medulla Thick coarse hair & beard hair always contain a medulla

Chemical Composition of Hair Hair is composed of protein that grows from cells originating within the hair follicle Keratinization Process during which newly formed cells in the hair mature They fill up w/ keratin, move upward, lose their molecules, & die The hair shaft is a nonliving fiber composed of keratinized protein

Chemical Composition of Hair 91% protein Cohns elements Carbon – 51% Oxygen – 21% Hydrogen – 6% Nitrogen – 17% Sulfur – 5% Amino acids Units of structure in protein

Chemical Composition of Hair Side bonds of cortex Middle layer of hair is made up of millions of polypeptide chains Cross-linked like a ladder by three different types of bonds Hydrogen bonds Physical side bond that is easily broken by water or heat They are weak individually, but because there are so many, they account for about 1/3 of the hair’s strength

Chemical Composition of Hair Salt bonds Physical side bond that is broken by changes in pH. Easily broken by strong alkaline or acidic solutions Account for about 1/3 of the hair’s overall strength Disulfide bonds Chemical side bond that differs greatly from the physical side bonds

Chemical Composition of Hair Disulfide bonds Chemical side bond that differs greatly from the physical side bond Join sulfur atoms of 2 neighboring cysteine amino acids to create cystine Far fewer than the physical bond, but are stronger Account for about 1/3 of the hair’s overall strength

Hair Pigment All natural hair color is the result of pigment located within the cortex Melanin Tiny grains of pigment in the cortex that give natural color to hair Eumelanin Provides brown & black color Pheomelanin Provides natural colors from red & ginger to yellow-blonde tones

Hair Pigment Natural hair color Gray hair Is the result of the ratio of eumelanin to pheomelanin, along with the total number & size of pigment granules Gray hair Caused by the absence of melanin. It grows in exactly the same way as pigmented hair but without the melanin pigment

Haircolor vs. Hair Color Hair Color ( two words ) refers to the color of hair created by nature. Haircolor ( one word ) is the term used in the beauty industry to refer to artificial haircoloring products.

Wave Pattern & Tendencies Described as straight Described as wavy Described as curly Described as extremely curly

Wave Pattern & Tendencies Straight hair usually round Wavy hair usually oval Curly/extremely curly almost flat

Wave Pattern & Tendencies Asians Extremely straight hair Caucasians Straight to wavy African-Americans Extremely curly

Summary Living cells form in the follicle and mature through keratinization Three layers of the hair is cuticle, cortex and medulla Hair has different wave patterns Next lesson – hair analysis