Biorheology of Loose Connective Tissues, Especially Blood Vessels

Abstract

To understand the physiological function of vital organs we must know the mechanical properties of the tissues. Experimental determination of the mechanical properties of living tissues has many difficulties, such as the small size of the specimens, large deformation, active contraction, damage due to dissection, disturbances in nervous and enzymatic actions, inaccessibility of the material, the non-existence of a unique “natural state,” and the necessity of keeping the specimens alive in an environment as much as in vivo as possible. These difficulties make the collection of data in biorheology a nontrivial endeavor. At present, biorheology is in an initial stage of development. In this article, major features of the rheology of loose connective tissues, especially the blood vessels, are summarized. A brief description of some new testing equipment will be given. A comparison between in vivo and in vitro experiments will be discussed. Differences of the mechanical properties of different tissues will be considered in relation to their materials of construction and geometric organization. Some comments about the mathematical description of the mechanical properties of soft tissues is offered to serve as a starting point for the analysis of the function of the organs.