  A simple model of cuprate superconductivity with an electron spectrum
prepared by doping is developed. The pair-transfer interaction couples the
itinerant band with two components ("hot'' and "cold'') of the defect
subsystem. There are basic defect-itinerant gaps quenched by progressive
doping. Band overlaps appear as novel sources for critical doping
concentrations. Insulator to metal transitions in the normal state are expected
here. Minimal quasiparticle excitation energies determine the pseudo- and
superconducting gaps according to the doping-dependent disposition of bands.
Two pseudogaps can be present at underdoping and two superconducting gaps can
be manifested at overdoping. Various transformations and connections between
the gaps agree qualitatively with versatile experimental findings. The
superconducting density does not reflect the presence of "extrinsic'' gaps
because of the interband nature of the pairing. A Uemura type sublinear plot at
underdoping with further recession is obtained. A mixed Fermi-liquid is
restored near optimal doping where the chemical potential intersects all the
band components. The metallization of the "cold'' subsystem is essential for
the rise of Tc on passing to optimal dopings.
