Short-term autonomic control of the cardio-respiratory system: a summary with the help of a comprehensive...

The system which provides short-term cardiovascular regulation has a very complex structure, resulting from the non-linear interaction among several different mechanisms: they include baroreceptors, peripheral chemoreceptors, lung-stretch receptors, a direct CNS response to hypoxia and hypercapnia, local vessel response to changes in blood gas content. Furthermore, during dynamic exercise a feedforward mechanism anticipates cardiovascular requirements, and interacts with the respiratory and muscle pumps. Aim of this work is to summarize the complexity of this system, and to point out the role of individual mechanisms and their mutual relations, with the help of a comprehensive mathematical model developed by the authors in previous years. Examples of system response are discussed during various acute cardiovascular perturbations (pressure changes, changes in blood gas content, dynamic exercise) and model results compared with existing data in the literature. These examples emphasize the great complexity, richness and variability of the autonomic cardiovascular control system. Simulations suggest that mathematical models and computer simulation techniques may represent essential tools to comprehend and deepen our understanding of complex, multifactorial systems, the behaviour of which cannot be fully revealed by simple qualitative analysis. Models play an important role in modern physiology as a repository of knowledge and to integrate disparate data inside an integrative coherent structure.