I thought that as depicted onscreen, the glowing part was the scoop that absorbed the desired particles. If it is not, and the gold vents are, then where is the corresponding part of the scoop on the TOS Enterprise?
There are also circumferential vents on the TOS Enterprise nacelles.
My feeling is that the Bussard collectors are a little inconsistently depicted on screen. In Star Trek: Insurrection and SNW: "Lost in Translation" the "glowy red bit" is specifically shown to suck up gas, which I believe to be a visual error, though in the case of SNW they have to physically open to do it, which is something we've never seen a Bussard do before. Indeed the TNG Technical Manual states that the nacelle end cap is the "largest single cast structure" of the whole ship, so it's one giant single piece, without holes, seams, perforations, or subcomponents.