Hair: Its structure and response to cosmetic preparations

Human Hair and the Impact of Cosmetic Procedures: A Review on Cleansing and Shape-Modulating Cosmetics

“…These cells only constitute a small percentage of the mass of keratin fibers. Medulla may be continuous, discontinuous or even entirely absent in the hair fiber [42,50]. Medulla is believed to contribute negligibly to the mechanical properties of hair fibers [47].…”

“…Human hair fibers are composed of different morphologic components and several different chemical species, acting together [45,50]. The main component is protein, corresponding to 65%-95% of the hair weight.…”

“…The main component is protein, corresponding to 65%-95% of the hair weight. Other constituents are water, lipids, pigment, and trace elements [50].…”

“…Several factors can induce changes in amino acid hair content, such as gender, genetic variation, weathering, diet, cosmetic treatment, as well as the extraction and analytical methods used. For example, in general, male hair contains more cystine than female hair and the tip of scalp hair contains, owing to weathering, significantly less cystine and cysteine than the root end; the converse applies for cysteic acid [50].…”

Biology of Human Hair: Know Your Hair to Control It

“…Products such as shampoos and conditioners, along with damaging processes such as chemical dyeing and permanent wave or relaxing treatments, alter many hair properties, which results in damage to the hair fibre [165][166][167]. In recent years, many innovations have taken place, and new approaches for hair treatments have been reported in the literature to overcome this problem.…”