What Are My Kidneys, and What Do They Do?

The kidneys are the main organs in your urinary system, responsible for filtering waste products from your bloodstream. Without your kidneys, your blood would fill with toxins and you would die pretty quickly. The kidneys also help keep your body in equilibrium, deciding how much water your body should get rid of, and how much water your body needs to retain to stay healthy.

Kidneys are shaped like their namesake, the kidney bean. Like the bean, kidneys are purplish-brown, and each is approximately the size if an adult fist. You can find your kidneys (hopefully) just above your waist on the backside of your torso, one on each side of your spinal column. Your adrenal glands sit on top of each kidney, but they are not connected in any way. The renal capsule and an inch of fat surround each kidney to protect these vital organs from injuries.

While a normal human is born with two kidneys, we really only need one kidney to function normally. If one kidney becomes damaged or is removed, the other kidney will grow fifty percent in about two months and completely take over for the missing organ.

The renal artery brings blood to the kidneys to be filtered, and the filtered blood is taken away from the kidneys by the renal vein. It only takes a minute for twenty-five percent of your body's blood to pass through your kidneys.

The kidneys dissolve the waste products from your blood in water to make urine. Each kidney has three layers. The outer layer is called the cortex, and that is where your blood is actually filtered. The middle layer of the kidney is the medulla, which drains the urine produced in the cortex to the inner layer of the kidney. The inner layer of the kidney is the renal pelvis, which passes the urine out of the kidney to the ureter. Our kidneys actually produce urine all the time; it is the rest of the urinary system that keeps us from constantly going to the bathroom.

The inward curve of the kidney is called the hillus. This is the part of the kidney where the renal pelvis attaches to the ureter. From the ureter, urine travels to the bladder where it gets stored. When the bladder signals to the brain that it is full, we go to the bathroom where the urine exits the bladder through the urethra.