This text addresses a simple question: are animals designed economically? The pronghorn can run at speeds of up to 60 kilometres an hour and can maintain this speed for nearly a full hour. Clearly, the form of this elegant animal is beautifully matched to the function it needs to perform. This is symmorphosis. The theory of symmorphosis predicts that size of the parts in a system must be matched to the overall functional demand. Moreover, it predicts that animals must provide their complex systems with functional capacity that can cope with the highest expected functional demands, possibly including some safety margin to prevent the system from failing when it is overloaded. In this book, the author tests these predictions by working out the quantitative relations between form and function. Physiologists will value this book because Weibel shows them that morphological information can be as quantitative as physiological data. Anatomists will value the book for its demonstration that advance integrative physiology crucially depends on adequate but rigorously quantitative and testable information on structural design.
Finally, anyone interested in the origins of the diverse forms of animals will be fascinated by Weibel's demonstrations that show how animals as different as shrews, pronghorns, dogs, goats - even humans - all develop from essentially the same blueprint by variation of design.
Ewald R. Weibel is Professor of Anatomy, University of Bern, Switzerland.
Preface Form and Function The Relation of Form and Function Adaptation of Function as a Design Principle Integration of Function as a Design Principle Economy as a Design Principle The Principle of Symmorphosis Cells and Tissues: Oxidative Metabolism in Muscle Energy Supply and Mitochondria Is Mitochondrial Structure Matched to the Demand for Oxidative Energy? Testing for a Quantitative Match of Form and Function in Muscle Mitochondria Is 6VO2 Related to V(mi) in Exercising Muscle Cells? Natural Variation in Energy Demand and Mitochondria Are Muscle Capillaries Adjusted to Mitochondrial Oxygen Needs? Symmorphosis in the O2 Pathway in Muscle Muscle: Supplying Fuel and Oxygen to Mitochondria Differences between Oxygen and Fuel Supply Variations in Fuel Supply to Mitochondria in Working Muscle Cells Partitioning of Fuel Consumption between Glucose and Fatty Acids Estimating the Capillary Supply of Substrates Revising the Model for Capillary Oxygen and Substrate Supply Fuel Supply from Capillaries versus Intracellular Stores Conclusions on Form and Function in Muscle Cells and Tissue Organ Design: Building the Lung as a Gas Exchanger Modeling Gas Exchange in the Lung A Large Surface and a Thin Barrier Determine the Gas Exchange Capacity of the Lung The Diffusing Capacity of the Human Lung How Much Lung Diffusing Capacity Do We Really Need? The Gas Exchanger of the Most Athletic Animal The Effect of Reducing the Gas Exchanger Conclusion Problems with Lung Design: Keeping the Surface Large and the Barrier Thin A Fiber Continuum Supports Parenchymal Structures Controlled Surface Tension Determines Parenchymal Mechanics Keeping the Barrier Dry and Thin Conclusion Airways and Blood Vessels: Ventilating and Perfusing a Large Surface Morphogenesis of Airways, Vessels, and Gas Exchanger Designing the Airway Tree for Efficient Ventilation Are Airways Designed as Fractal Trees? Conclusion The Pathway for Oxygen: From Lung to Mitochondria Testing the Hypothesis of Symmorphosis The Strategy: Exploiting Comparative Physiology The Model and Predictions Testing the Respiratory System for Symmorphosis Does Symmorphosis Prevail in the Respiratory System? Adding Complexity in Form and Function: The Combined Pathways for Oxygen and Fuels Strategies for Oxygen and Fuel Supply Design of the Fuel Supply Pathway Design of Nutrient Uptake Systems The Substrate Pathways for Fueling Muscle Work The Test of Symmorphosis On Symmorphosis in Complex Pathways Symmorphosis in Form and Function: Concepts, Facts, and Open Questions How to Perform a Test of Symmorphosis: Future Prospects Conclusions References and Further Reading Index