[en] The generalized longitudinal charge-spin susceptibility functions and the collective excitations of spin-polarized quantum structures are investigated within the framework of spin-dependent linear response theory. We evaluate the charge response and the longitudinal spin response to a general external disturbance. Exchange-correlation effects between electrons of spin σ and σ' are included by using spin-polarization dependent generalized local field factors. Both collective charge-density and spin-density excitations are examined. The present results are compared with the case of a spin-unpolarized system. In contrast to the result for an unpolarized system, the mixing of charge and spin responses results in coupled charge-spin excitations in the spin polarized system