What are the two main components of a mature strand of human hair?

A mature strand of human hair is primarily composed of two main components: the cuticle and the cortex. The cuticle is the outermost layer of the hair, consisting of overlapping, scale-like cells that protect the inner structures. The cortex, located beneath the cuticle, contains the majority of the hair's protein structure and is responsible for the hair's strength, color, and texture.

While the root and bulb are important parts of the hair structure, they are not components of the hair strand itself; rather, they play roles in the hair's growth and regeneration. The hair root anchors the hair in place, and the bulb is the part of the hair follicle from which the hair grows. The hair shaft, which is the visible part of the hair, is formed primarily of the cuticle and cortex.

The medulla is another layer that can be found in some hair types, but it is not present in every strand, and its significance varies among individuals. Therefore, focusing on the cuticle and cortex provides a clearer understanding of the essential components that comprise a mature strand of hair.