Respiration, circulation and excretion

Abstract

This chapter deals with three interdependent systems. Pressurized filtration by the kidneys is affected by the affairs of the three hearts and these in turn by the movements of the mantle. Each is under nervous control and each must take into account the activities of the other two if it is to perform correctly. Research on the performance of the three systems has, however, usually been concerned with one system at a time and generally with one aspect of performance at a time. Sooner or later we shall have to try and monitor nerve impulses, pressure changes, oxygen and metabolite concentrations simultaneously, since these observations will undoubtedly reveal some very elegant control mechanisms. In the meantime, one is obliged to consider the workings of the three in the classical manner, one at a time; remembering that, eventually, the bits will patch together to yield a much more beautiful story.