ectormorph: narrow shoulders, long limbs, fast metabolism, and relatively skinny; usually have a hard time gaining muscle
mesomorph: more muscle than fat, fast metabolism, naturally muscular looking, relatively easy muscle gain
endomorph: more fat than muscle, however it's relatively easy for them to gain muscle
These are just the main qualities of the different body types based upon natural/environmental circumstances. With resistance and endurance training you can change your body type, because you can lose mucle/gain muscle and train muscle fibers to act differently.
As far as timings of anabolism and catabolism, they're costantly occuring.