New Jersey Cosmetology and Hairstyling Practice Exam

Which part of the hair strand is the most resistant to chemical processes?

1. The medulla

2. The cortex

3. The cuticle

4. The root

The correct answer is: The cuticle

The cuticle is the outermost layer of the hair strand and plays a crucial role in protecting the inner layers. It consists of overlapping scale-like cells that help shield the hair from environmental damage and chemical treatments. Due to its structure, the cuticle acts as a barrier, making it the most resistant part of the hair strand to chemical processes. This resistance is primarily because the cuticle's tightly packed and overlapping cells prevent chemicals from easily penetrating into the deeper layers of the hair. While the cortex, which lies beneath the cuticle, is important for providing strength and contributes to the hair's overall structure and appearance, it is more reactive to chemical processes and is where most chemical treatments, like coloring or perming, work. The medulla, which is the innermost layer, is not always present in every strand of hair and generally does not play a significant role in chemical resistance. The root is found below the surface of the skin and is not part of the hair strand itself, making it irrelevant in the context of chemical processes affecting the hair shaft.