We present high-resolution echelle spectroscopy of a sample of H II galaxies. In all galaxies we identify different Hα-emitting knots along the slit crossing the nucleus. All of these have been isolated and separately analyzed through luminosity and size versus σ diagnosis plots. We find that in all cases, for a particular galaxy, the bulk of the emission comes from their main knot and therefore, at least for the compact-class galaxies we are dealing with, luminosity and σ values measured using single-aperture observations would provide results similar to those obtained with spatially resolved spectroscopy. In the size versus σ plots, as expected, there is a shift in the correlations depending on whether we include all emission in a single point or split it into its different emitting knots. The problem of a proper determination of the size of the emitting region so that it can be used to determine the mass of the system remains open. From the data set gathered, using the highest surface brightness points as recently proposed by Fuentes-Masip et al., the best luminosity versus σ correlation turns out to be consistent with a Virial model.