Simply put, all the colors are comprised of three sets of complementary colors:
Red     < - >  Cyan
Green  < - >  Magenta
Blue    < - >  Yellow

When adjusting a color, you affect its complementary color as well. For example:

1. By increasing amount of Red color in an image, you are also decreasing Cyan; if you decrease Red, you automatically increase Cyan.

2. If you reduce Green ( - ), the amount of Magenta grows ( + ); adding Green ( + ) subtracts Magenta ( - ). 

3. Increasing ( + ) Blue, reduces ( - ) Yellow; increasing ( + ) Yellow, subtracts ( - ) Blue.

And so on... Also bear in mind this relationship when you use channels for color adjustments.
Select the Red channel to adjust red and cyan colors, select the Green channel for greens and magentas and select the Blue channel for blues and yellows.