Macromolecular orientation and tissue mechanics: a comparative study of blood vessels, skin and tendon

Incremental stress-strain analyses were performed on vascular tissues and compared with the results of similar studies on skin. Incremental testing allows the separation of the elastic and viscous components of stress-strain behavior. Both elastic and viscous stress-strain curves consist of two regimes; low and high strain regions that are both approximately linear. In vessel wall, low strain elastic behavior is consistent with previous studies, which suggest that behavior in this regime is dominated by elastic fibers. High strain elastic behavior is different than in skin and tendon, where the data is consistent with the collagen fibers bearing the load. It is concluded that blood vessels act differently than other connective tissue due to the organization of collagen with smooth muscle cells (smc). A model is proposed indicating a series collagen-smc elements in parallel with elastic tissue. This arrangement may be important for smc mechanochemical transduction and efficient auxiliary pumping by the vessel wall.