Abstract
A model of dynamical and chemical evolution for spheroidal and disk galaxies is discussed. The star formation rate in the model is regulated by ionization of the interstellar hydrogen by massive O,B stars. The volume of a galaxy is determined by the condition of equilibrium between collisional dissipation of turbulent energy of interstellar gas and turbulisation of the gas by supernovae. The modern theory of stellar evolution helps to describe evolution of the stellar component of a galaxy in time and to estimate the current frequency of supernovae. This model reproduces some basic observed parameters of spheroidal and disk galaxies and their evolution on the Hubble timescale. The role of external factors in evolution of galaxies and possible reasons of a nonstationary star formation in galaxies and their nuclei are shortly discussed.
