[William Harvey reinterpreted in the light of species evolution (I) - How and why circulation phylogenesis integrates...

In this first part we describe the different steps of the evolution of species and the circulatory modifications, which accompany it. From the open circulation in invertebrates, via the in-series closed circulation in fish, to the in-parallel closed circulation in mammals, the local ability to vasodilate in relation to the specific metabolic demand of territorial activity was the driving force for circulatory evolution. This capacity was achieved by the progressive muscularization of small arteries, generating frictional forces, which systemically determine high arterial pressure, and locally determine active vasodilation via the inhibition of vasomotor tone. This determinism differentially impacts the small resistance arteries, which generate blood pressure, and the large conductance arteries, which support the tensional stress generated by the blood pressure.