Topic 3 Summary

Hair is composed of a fibrous protein, keratin, which originates in the hair follicle. The hair is made up of long amino acid chains joined to each other by peptide bonds. This bond is the backbone of all protein molecules. The polypeptide chains are wound around each other in the form of a helix. When the amino acids combine, they form the keratin protein of hair. Hair is made of two solids, carbon and sulfur, and three gases, hydrogen, nirtogen, and oxygen. The long spiraling protein chains are placed next to one another and are linked together by four side bonds. The four side bonds are the hydrogen bond, the salt bond, and the disulfide bond. The fourth bond is called van de Waal's Forces. This particular bond is based on the theory that atomic groups prefer an environment with other groups that have structures similar to theirs. This does not affect hairstyling services, students just need to know that they exist.

The hair gets its color from a pigment known as melanin. The color of a person's hair is determined by their genes. Melanin is procuded by melanocytes, cells that exist near the hair bulb. They collect and form bundles of a pigment protein complex called melanosomes. The size, type, and distribution of the melanosomes will determine the natural color of the hair.

There are two types of melanin, eumelanin which is brown/black in color and phaeomelanin which is red. Gray hair is caused by reduced color pigment in the cortex layer of the hair. Gray hair is a natural process in aging and often times serious illness or emotional conditions can cause the hair to gray prematurely.