Mechanical design in arteries

The most important mechanical property of the artery wall is its non-linear elasticity. Over the last century, this has been well-documented in vessel s in many animals, from humans to lobsters. Arteries must be distensible to provide capacitance and pulse-smoothing in the circulation, but they must also be stable to inflation over a range of pressure. These mechanical requ irements are met by strain-dependent increases in the elastic modulus of th e vascular wall manifest by a J-shaped stress-strain curve, as typically ex hibited by other soft biological tissues. All vertebrates and invertebrates with closed circulatory systems have arteries with this non-linear behavio ur, but specific tissue properties vary to give correct function for the ph ysiological pressure range of each species. In all cases, the non-linear el asticity is a product of the parallel arrangement of rubbery and stiff conn ective tissue elements in the artery wall, and differences in composition a nd tissue architecture can account for the observed variations in mechanica l properties. This phenomenon is most pronounced in large whales, in which very high compliance in the aortic arch and exceptionally low compliance in the descending aorta occur, and is correlated with specific modifications in the arterial structure.