Nails are primarily composed of which substance?

Nails are primarily composed of keratin, which is a type of protein that is also found in hair and skin. Keratin provides strength and resilience to the nails, making them hard and protective. The structure of keratin allows it to form layers that protect the underlying tissues of the fingers and toes. This characteristic is essential for the overall health and function of the nails, as they serve both a protective role and assist with the manipulation of objects.

In contrast, collagen, another protein found in the body, primarily contributes to the structure of skin, tendons, and bones, but it is not a component of nails. Elasticin, also known for its presence in connective tissues, provides elasticity to skin and other structures, but it does not play a role in nail composition. Chitin is a structural component found in the exoskeletons of arthropods and in the cell walls of fungi, but it is not relevant to human nails. Thus, keratin stands out as the essential substance that makes up the structure of nails.