othalamus monitors the amount of water in the body by sensing the concentration of electrolytes in the blood; a high concentration of electrolytes means that the level of water in the body is low.Antidiuretic hormone (ADH), produced by the hypothalamus and RELEASED by the posterior pituitary, causes more water to be RETAINED by the kidneys when water levels in the body are low.ADH EFFECTS water retention by creating special channels for water, called aquaporins, inside the kidneys so that more water can be reabsorbed before it is excreted.Aldosterone, produced by the adrenal cortex, causes the retention of water in the body by INCREASING the levels of sodium and potassium ions in the blood, which causes the body to REABSORB more water.When blood pressure is low, the enzyme renin is released, which cleaves the protein angiotensinogen into angiotensin I, which is further converted into angiotensin II.Angiotensin II signals the adrenal cortex to release aldosterone, which then increases the retention of sodium ions, enhancing the secretion of postassium ions, resulting in water retention and an increase in blood pressure.