Which part of the hair serves as its primary defense?

• A. Cuticle
• B. Cortex
• C. Medulla
• D. Dermis

Answer: (A)

The outermost protective layer of the hair, the cuticle, serves as the primary defense. It’s made of overlapping scale-like cells that form a shield around the inner parts of the hair shaft. This outer layer protects the cortex (which provides strength and color) and the medulla (the hair center, which isn’t always present) from physical damage, chemical exposure, and moisture loss. When the cuticle is smooth and intact, the hair is more resistant to breakage, holds moisture better, and has a healthier appearance. If the cuticle is damaged, the hair becomes rough, more prone to frizz and further damage. The dermis is skin tissue around the hair follicle, not part of the hair shaft itself, so it isn’t the hair’s protective layer.