The General Structure of Hair
All hair is made up of similar components. Hair is composed of keratin, the same protein that makes our nails.
Each strand of hair consists of the cuticle, the outer layer of hair; the cortex, the middle layer which contains melanin, the substance that gives the hair its color; (Thicker strands of hair contain the medulla, which is the inner most layer.)
Below the skins surface is the hair root and the structure that it sits in is called the follicle. The follicle widens as it goes down into the hair bulb. It is here where the hair is nourished by the dermal papilla - which is feed by the blood steam - which produces new hair.
Because hair grows from the inside out, what your put on the actually hair is not as important as what you put in your body. Diet, health and lifestyle will affect your hairs grows inside and looks outside as much as the products that you use to care for it.
The shape of the follicle will determine the shape of the hair. The more curved the follicle is the more curved the hair will be and vice versa.