MOVEMENT OF MUCUS IN LUNG

Three mechanisms for mucous transport in the lung, namely due to cilia, gravity and interaction with the airflow are investigated. Mucus removal due to cilia is considered in terms of a theoretical model involving an infinite array of flexing slender bodies. Oscillatory velocities of the order of magnitude sigma L( sigma equals radian frequency, L equals length of cilium) and shear rates of order sigma are calculated. The gravity and airflow effects are investigated in terms of a two layer Newtonian fluid model: the results indicating that mucous movement depends critically on the viscosity and depth of the lower serous layer and that both of these mechanisms can be far more important than has been previously indicated. Discussions on the reversing airflow models and visco-elasticity of the mucus are presented.