The hair cortex is the main ingredient of hair, consisting of slender cells that are parallel to the long axis of hair. In these cells there are about 10 mm of tension filaments and interstitial stroma, which determine the main physiological traits of hair. Filaments consist of fibrous proteins, of which 50% of the proteins are spiral-shaped, and the matrix is composed of cysteine-rich non-helix proteins. These proteins are synthesized at the lower end of the follicle and the final phase of the synthesis of cysteine converts to cystine.
The physical properties of hair are related to their chemical compositions. Soak the hair in the water, it will swell quickly, the swelling after the weight is more than 40% percent before the dry, the water swelling phenomenon indicates that the hair is almost purely a protein component, and the lipid content is very low. The hair has a strong duality, which is due to the alignment of filaments in the cell with the long axis of the hair.