<prompt> The most powerful feedback system for controlling plasma osmolarity and sodium concentration isADH and thirstSaltAngiotensin renin systemAngiotensin rennin system  <response>: If osmotic pressure of the plasma is increased more than normal then the osmoreceptors are activated and ADH secretion increased. Theres more receptors causes thirst and increase in the water intake. Daddy secretion causes water retention. This leads to dilution of ECF. Ref: page no 564 Textbook of physiology Volume 1 7th edition AK Jain 