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.