Hierarchical Structure of Collagen and its Relationship to the Physical Properties of Tendon
This chapter illustrates the role of the hierarchical structure of collagen in determining the physical properties of a tissue using the tendon. This tissue serves as the primary linkage between muscle and bone and functions mainly in uniaxial tension. The effects of maturation and aging on collagen fibrils are described including the role of water content in the extrafibrillar matrix. The universality of hierarchical structure in collagenous tissues is examined. In particular, a comparison will be made between tendon, intestine, and intervertebral disk. The hierarchical structure of tendon is designed to accommodate uniaxial tensile forces and as such is organized as an anisotropic material. The effect of aging on the mechanical response of tendon to uniaxial tension has been studied extensively. The changes observed during maturation are manifested in all regions of the stress-strain curve while those associated with aging of a mature organism appear only in the toe and damage regimes.