Cosmetology Anatomy & Physiology Practice Test

The main structural component of hair is keratin. Keratin is a type of fibrous protein that makes up not only hair but also nails and the outer layer of skin. It provides strength, resilience, and protection to hair, allowing it to withstand various external factors. The unique structure of keratin includes a helical formation that contributes to the tensile strength of hair strands, making them durable yet flexible.

Collagen is primarily found in the dermis layer of the skin and is responsible for providing structure and elasticity, but it is not a component of hair itself. Elastin is another protein that helps maintain skin elasticity and is not involved in the composition of hair. Melanin, on the other hand, is responsible for the pigmentation of hair and skin, but it does not contribute to the structural makeup of hair. Thus, keratin stands as the primary material that gives hair its strength and structure.