  We study the effects of mergers on the structural properties of disc-like
systems by using Smooth Particle Hydrodynamical (SPH) numerical simulations in
hierarchical clustering scenarios. In order to assess the effects of mergers on
the mass distributions we performed a bulge-disc decomposition of the projected
surface density of the systems at different stages of the merger process. We
assumed an exponential law for the disc component and the S\'ersic law for the
bulges. We found that simulated objects at $z=0$ have bulge profiles with shape
parameters $n\approx 1$, consistent with observational results of spiral
galaxies. The complete sample of simulated objects at $z=0$ and $z>0$ shows
that $n$ takes values in the range $n\approx 0.4 - 4$. We found that secular
evolution tends to produce exponential bulge profiles, while the fusion of
baryonic cores tends to increase the $n$ value and helps to generate the
correlation between $B/D$ and $n$. We found no dependence on the relative mass
of the colliding objects. Our results suggest that mergers, through secular
evolution and fusions, could produce the transformation of galactic objects
along the Hubble sequence by driving a morphological loop that might also
depend on the properties of the central galactic potential wells, which are
also affected by mergers.
