The modelling of physiological systems presents particular challenges. Events at the level of individual channels and receptors can affect the behaviour of an entire organ, via their control of cellular behaviour, and thus models need to span a wide range of spatial and temporal scales. However, despite their similarities, multiscale models also show great diversity, which requires a similar diversity of approach for their solution. I shall consider two multiscale models in particular, one of the lung, one of the parotid salivary gland. Although both are multiscale, they are quite different in their essential natures. Our model of the lung relates the intracellular dynamics of calcium in airway smooth muscle cells to function at the level of the entire lung, taking into account along the way such matters as fluidisation of lung tissue and the development of heterogeneity in the lung. Our multiscale model of the parotid salivary gland is, on the other hand, quite a different beast. Although calcium oscillations again are the major determinant of behaviour, in this case the structure of the gland and the properties of fluid transport suggest that the behaviour of the entire gland can be simply reduced to the behaviour of single cells, in which case our 'multiscale' model is perhaps not so very multiscale after all.