Cilia Powered Pumps
Ciliated organs are fundamental micro-pumps in animal biology that drive luminal fluids via the coordinated activity of thousands of internal cilia. While the structure of individual cilia is remarkably conserved across the animal kingdom, the morphology of ciliated organs vary drastically and so does their physiological function. Examples range from cilia-powered transport and clearance of fluids in the mammalian respiratory, reproductive, and cerebrospinal systems to cilia-powered filtration and waste excretion in small invertebrates. Despite progress in analyzing specific models, the relationship between the structure of ciliated organs and their fluid pumping function remains opaque. Here, using mathematical modeling, experimental studies in animal models, and a survey of ciliated organs across all animal phyla, I will discuss two aspects of cilia structure-function relationship. I will show that cilia can spontaneously organize into traveling wave patterns that break symmetry and pump fluids. Then, I will explain how the morphology of ciliated organs directly predicts whether they are optimized for fluid transport or filtration. Our work suggests that the convergence of ciliated organ designs in the animal kingdom is based on functional constraints rather than phylogenetic distance, and establishes design rules for bio-inspired and tissue engineered cilia powered pumps.