What are the different parts of a hair strand?

The different parts of a hair strand consist of the cuticle, cortex, and medulla. The cuticle is the outermost layer, composed of overlapping, scale-like cells that protect the inner structures of the hair and contribute to its shine and smoothness. The cortex is the dense middle layer, making up the bulk of the hair strand; it contains keratin and plays a significant role in the hair's strength, color, and texture. Lastly, the medulla is the innermost layer, which is not always present in every hair type. Its function is still being researched, but it may contribute to the overall strength and structure of the hair.

Understanding these parts is essential for various hair care practices, as they can impact how hair should be treated in terms of washing, conditioning, styling, and chemical applications. Other options presented describe components related to hair growth cycles or general characteristics, but they do not accurately represent the physical structure of a hair strand.