Fluid balance is maintained by ensuring that the amount of water consumed through food and drink is equal to the amount of water excreted. One way our body pushes us to work to maintain water balance is through thirst and cravings for salt. The kidneys are the most important factor in water excretion, although we lose water elsewhere, it is mainly lost through the kidneys. Our kidneys maintain control of fluid volume by controlling the amount of water excreted through urine, the kidneys are able to conserve water by producing concentrated urine compared to plasma or they can ensure that they eliminate excess water by producing urine that it is diluted compared to plasma. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay Vasopressin (antidiuretic hormone, ADH) is a peptide hormone produced by the hypothalamus and is responsible for directly controlling water excretion through the kidneys. ADH is responsible for inserting water channels into the cell membranes where it will line the collecting ducts which allow water to be reabsorbed, with a lack of ADH little water will be reabsorbed into the collecting ducts and dilute urine will be produced. Anything that stimulates ADH secretion also stimulates thirst. A couple of factors that influence ADH secretion are as follows. Special receptors within the hypothalamus that are sensitive when plasma becomes too concentrated and stimulate the secretion of ADH. There are also stretch receptors present in the atria of the heart which can be activated by a larger than normal volume of blood returning from the heart to the veins, this will inhibit the secretion of ADH as the body will have excess fluid that it wants to get rid of . . Stretch receptors are also present in the aorta and carotid arteries and are stimulated when blood pressure begins to drop, it stimulates the secretion of ADH because the body needs to maintain sufficient volume to generate the blood pressure needed to maintain a pressure normal blood supply capable of effectively supplying blood to tissues. Total volume isn't the only thing tightly controlled, osmolarity (amount of solute per unit volume) is also tightly regulated. The change in osmolarity will cause the cells to shrink or swell, damaging or even destroying the cell structure and disrupting normal cell function. To control it, the body balances sodium intake and excretion with that of water since sodium is the major solute in extracellular fluids effectively determining the osmolarity of extracellular fluids. Osmolarity must be integrated with volume regulation as changes in water volume will have a diluting or concentrating effect on body fluids. When you become dehydrated you lose more water than solute and as a result the osmolarity of your body fluids increases, your body wants to conserve water and not sodium, which causes the osmolarity to increase. However, if you lose a lot of blood due to trauma, your losses of sodium and water will be proportionate to the composition of your body fluids and therefore your body will need to conserve both water and sodium as needed. ADH also plays a role in reducing sodium concentrations by increasing the amount of water reabsorption in the kidneys by helping the body dilute body fluids. The kidneys have a regulated mechanism responsible for reabsorbing sodium in the distal nephron if osmolarity drops below normal. The mechanism is controlled by the use of aldosterone which is a steroid hormone produced in the adrenal cortex. First of all the bark.