hair colors and henna Flashcards
three layers of hair:
- cuticle (outer part)
- the cortex (main body of hair shaft)
- medulla (innermost, airspace)
which part of the hair is thought to cause insulation (air pockets)?
the medulla
the cortex contain natural moisture and pigment
true
it is visible through the translucent cuticle because the cuticle is like a window
what is the cortex structure responsible for?
straightness, curliness, and elasticity
the medulla varies in form and proportion
true
the translucent scales of the cuticle are overlapping theyclose and open like a window angle
true
which protein does hair consist of?
keratin
(18 amino acids bound to alpha helix, look like a coiled spring)
springs are held together by 3 types of bonds between chains & coilds
what gives hair elasticity, bounce and strenght?
the springy shape.
even sraight hair has underlying coild structure
what bonds are the strongest and what can break them?
- disulphide bonds are the strongest
- can be broken by perming, relaxing or bleaching
what bonds are the weakest and easily broken?
hydrogen bonds and salt bonds
how are the weakest bonds broken?
hydrogen bonds are stretched when wet
salt bonds are easily broken by weak acids or weak alkalis
bonds that allow hair to be shaped into temporary style by setting or blow drying:
hydrogen and salt bonds
texture is the diameter of a single hair
true
hair can be in any texture from very coarse to very fine and diameter is determined by genes
texture can also refer to the relative curliness or straightness
to the shape of cross-section
the shape of cross-section that texture can refer to
- flat section: curly hair
- round section: straight hair
hair properties
texture, porosity, hydroscopicity, elasticity
what is porosity & hygroscopicity & elasticity
a measurment of the hair ability to absorbs moisture
hygroscopicity measures the hair ability to absorb water vabor
elasticity is the ability of the hair to strecth and return to its original shape