The kinematics and mechanics of muscle's myofilament lattice

Abstract

By integrating the actions of millions of molecular motors, muscle cells power the movements of entire organisms. This multiscale system is tuned both by the geometry of the lattice of sub-cellular molecular machinery and by the interactions of the body with the environment. In this thesis, we review the structure of the molecular machinery and the seminal theories of muscle contractility. We document the movements of the molecular machinery using x-ray diffraction in a naturally functioning organism, where multiscale interactions remain intact, revealing how the lattice changes shape as a result of nervous activation. And guided by the observed structure and motions of the lattice of molecular machinery, we use a finite element model to investigate the flow of fluid and the viscous drag forces between the molecular machinery and the surrounding cytosol. These studies are a window into the elegant sub-cellular mechanisms that give rise to diverse functions at the organism scale.