What connective tissue protein is known for its strength and found in various body parts?

Collagen is the primary connective tissue protein recognized for its strength and structural support in the body. It plays a crucial role in forming the framework of various tissues, including skin, tendons, ligaments, cartilage, and bones. This protein provides tensile strength and helps in maintaining the integrity and resilience of tissues, allowing them to withstand stretching and stress.

In addition to its structural functions, collagen is also essential for wound healing and tissue repair. The body synthesizes different types of collagen, each suited to specific functions within different tissues. Its abundance and versatility make it a fundamental component in medical and rehabilitation practices, especially in physical therapy, where restoring movement and strength in the musculoskeletal system is critical.

The other proteins listed have different roles or properties. Elastin, for example, provides elasticity and allows tissues to stretch and return to their original shape, which is important in areas such as skin and blood vessels. Keratin is primarily a protective protein found in hair, nails, and the outer layer of skin, contributing to their hardness and impermeability. Fibrin plays a different role altogether, being involved in the clotting process of blood, helping to form a mesh that stops bleeding. Therefore, collagen's unique characteristics as a strong connective tissue protein distinctly