What makes up a mature hair strand?

A mature hair strand is primarily composed of two main components: the root and the shaft. The root is the part located beneath the skin, within the follicle, where the hair grows and receives nutrients, while the shaft is the visible part of the hair that extends above the skin. The interaction between the root and available nutrients enables the hair to grow and maintain its structure.

While the other components mentioned in different choices, such as the cortex and cuticle, refer to specific layers of the hair strand, they are not the primary components that define a hair strand as a whole. The cortex provides strength and color to the hair, and the cuticle serves as a protective outer layer, but these layers are not standalone components. The terms "pelage" and "medulla" refer to hair types and structures that are not typically included in the standard anatomy of a mature hair strand.

Understanding the distinction between root, shaft, and the other layers will assist in grasping the complex nature of hair health and growth as a fundamental aspect of cosmetology.