[Modeling of unstable heat-mass air exchange in the lungs]

A mathematical model of the unsteady-state heat and mass exchange of expired air in the bronchial tree is suggested. The model includes heat and mass exchange between air and bronchial walls, and heat exchange between blood circulation and bronchial tree. A problem has been numerically solved as a unidimensional one in the quasi-steady-state formulation. It is shown that air conditioning occurs through the whole length of a respiratory tract. During inspiration bronchial walls are cooled, that in its turn induces a decrease of air temperature and water vapour content in time. That process depends on the intensity of lung blood circulation and character of air velocity changes during inspiration.