  In this work, a compilation of effective electromagnetic field couplings to
pions and constituent quarks and their effective interactions derived
previously, including corrections to the NJL model, is presented. The
particular case of a weak external magnetic field along the $\hat{z}$ direction
is considered shortly and effective coupling constants are redefined to
incorporate the weak-$B_0$ dependence. They correspond to corrections to well
known pion-constituent quark couplings and to the NJL and vector NJL effective
couplings that break isospin and chiral symmetries.
