On mucociliary transport

The periodically changing flow pattern in the mucus layer which lies between the ciliary tips and the transported load is discussed and analyzed. The resulting energy dissipation per cilium is estimated, as is the energy dissipated per cilium in the periciliary fluid. The rate of supply of energy to each cilium by far exceeds these two loss rates. It is shown why the elastic character of mucus is important for good momentum transfer from cilium to load and for good load carrying properties. Fast flow requirements upon secretion of mucus, on the other hand, make it desirable that elasticity and viscosity be low as possible. A compromise is needed and the rheological character of mucus is matched to satisfy these opposing demands.