All about hair!
Basic Structure of Hair:
The hair shaft has three parts, the cuticle, the cortex, and the medulla. The cuticle is the clear outside covering of the hair shaft. It is made up of tough overlapping scales. The cortex is made up of keratin molecules. Keratin is tough protein made up of about 20 different amino acids. In the cortex is the pigment that makes our hair black, brown, blonde, or red. If we didn't have that pigment our hair would be gray or white. And, that's the cause of gray and white hair. The medulla is a row of cells that run along the center of the cortex. It sometimes appears dark or translucent depending on whether there is air, liquid, or pigment in it. Human hair generally has no medulla or one that is fragmented.
There are several different possible shapes of hair, as you know. Hair can be straight, curly, or kinky, depending what what the cross section of the shaft looks like. Straight hair tends to be round, curly hair tends to be oval, and kinky hair tends to be the shape of a crescent moon. The cross section of the shaft tends to look like those shapes, that is.