Fluid Balance

The kidneys are bean like shaped organs, which are roughly the size of a fist. The kidneys on average filter about 150 liters of blood every day to sieve out waste products and extra water, The waste and extra water is then turned into urea which becomes urine, this is then sent to the bladder through tubes called ureters, it then exits the body via urine.
The Wastes found in the blood come from the breakdown of active tissues, such as muscles and from food. The body uses food for energy (glucose), once the body has got what it needs from the food, the waste and bits not needed are sent to the blood. The waste is then sent to millions of small units inside the kidneys called nephrons, Inside a nephron is a glomerulus, which is a tiny blood vessel or capillary that has a small tube which collects urine, this is called a tubule. The glomerulus sieves out and keeps the proteins and cells in the bloodstream, allowing extra fluid and wastes to pass through. A chemical exchange takes place, as the waste materials and extra water leave the blood and enter the urinary system to leave the body.
The tubules receive waste materials and chemicals the body can still use, The kidneys then filter out the chemicals such as sodium, phosphorus, and potassium and send them back to the blood to return to the body. The kidneys regulate the body's level of these substances and ensure it has the correct balance. The kidneys also release three types of hormones, Erythropoietin which makes red blood cells, rennin which regulates the body’s blood pressure and calcitriol which helps to maintain the calcium for bones.