  We consider a U(5)-Nambu-Jona-Lasinio model with flavor-dependent couplings
constants obtained from quark-antiquark polarization to investigate the role of
the heavy quarks for light constituent quarks and mesons. A quantum mixing, due
to the different representations of the flavor group needed to defined quarks
and mesons, lead to charm and beauty sea quark contributions to properties of
the light quark sector. For a given fitting procedure for the parameters of the
model, the charm and beauty quark effective masses are freely varied from very
small values to very large values (infinite). The effect of these variations on
pion and kaon observables, such as masses, weak decay constants and
condensates, is calculated. Although the pion mass can vary (seemingly too
much) up to $20\%$ for a very large variation of heavy quark effective masses,
their contributions for the kaon mass are at most of the order of $2\%$ and all
the other variables and observables, including up and down quark constituent
masses, vary at most around $1\%$.
