Mechanisms of Systemic Regulation: Respiration and Circulation

Various endogenous and environmental challenges of homoiostasis have resulted in the evolution of apparently quite different mechanisms for the same or similar functions in individual representatives of the animal kingdom. One of the prominent achievements of comparative physiology over the last few decades has been the description of regula- tory features common to many studied species beyond the extreme diversity of their morphological forms. Delineation of functional princi- ples universally applicable to the physiology and biochemistry of living systems became often possible through technical advances in the devel- opment of numerous new techniques, in many cases modified and adopted from other fields of science, but also by approaching certain problems using multifactorial analysis. The advance in technology has facilitated studies of minute functional details of mechanisms, which finally lead to better understanding of generally similar functions, covered by the multiple developments of Nature as a response to an extreme variety of different conditions. Improved understanding of specific mechanisms, however, has presented new problems at the level of system integration. The importance of the integrative aspect became particularly apparent during an international symposium on 'Mecha- nisms of Systemic Regulation in Lower Vertebrates: Respiration, Circu- lation, Ion Transfer and Metabolism' (organized in 1990 by Norbert Heisler and Johannes Piiper at the Max-Planck-Institut flir experimen- telle Medizin at Gottingen/Germany).

This volume presents aspects of cellular mechanisms and generalized functions related to import and export of substance, intracorporeal transfer and maintenance of the overall status of animals: gas exchange, with special emphasis on cutaneous mechanisms, the role of carbonic anhydrase for CO2 elimination in aquatic animals, the interaction between blood gas transport and metabolic function in the swim bladder, and the regulation of ventilation by CO2/pH chemoreceptors at various locations; the ionic control mechanisms affecting oxygen transport in nucleated erythrocytes of fish species; the mechanisms governing central vascular circulation and the separation of oxygenated and deoxygenated blood in reptilia; the effects of phylogenetic and ontogenetic development on the regulation of circulation in amphibia; the physiological function of the venolymphatic system and the branchial secondary circulation in amphibia and fishes.