Long-term phase The renal-body fluid pressure control mechanism this mechanism can eventually return the arterial pressure all the way back, not merely partway back, to the pressure level that provides normal output of salt and water by the kidneys Days. Weeks and years kidneysLong-term phase mechanism: this mechanism can eventually return the arterial pressure all the way back, not merely partway back, to the pressure level that provides normal output of salt and water by the kidneys The renal-body fluid pressure control ----kidneys ----------Days. Weeks and years