The Kidney/Renal System

The Renal or Urinary System
The urinary system’s job is to eliminate waste from the body and bloodstream. Specifically, it’s job is to eliminate urea from the blood. Excess water and other byproducts from digestion are also waste. They are filtered out of the body by the urinary system through urine.

Image Courtesy of Stanford Children’s Health

Components of the Renal System
The renal system is made up of the kidneys, ureters, bladder and urethra. There are two kidneys each connected to a ureter. The ureters carry the urine to the bladder where it is held for elimination. The urine leaves the body through the urethra.

Everyone has two kidneys. They are located underneath the ribs and in the back of the body. Their job is to remove the waste from your blood. Their job is to balance vitamins, water, and other substances in the blood. They also produce erythropoietin which helps produce red blood cells in the body. The kidneys have nephrons that help filter the waste. Each kidney has a glomerulus (which is a ball of capillaries) and a renal tube to remove the waste. Urine is produced from this process, which then carries the waste out of the body.

These are connective tubes that run from each kidney to the bladder. They carry urine from the kidneys to the bladder. They squeeze and contract to move the urine on a continual basis from the kidneys to the bladder. If they do not move the urine and it stands still inside of the tubes an infection can occur.

This is an expandable organ that holds urine until it’s ready to be excreted through the urethra. It is located in the lower abdomen above the pubic bone. The bladder can grow larger to hold more urine. It then squeezes and flattens to release the urine into the urethra. Your bladder contains a special set of nerves to alert the brain it’s full and needs to be emptied. Thus, you feel the need to pee.

This is the tube that opens to the outside of your body to eliminate urine from the bladder.

How Does the Renal System Work Then?
The most complicated part of this system is the kidney. It is more complex than the other components of this system. The kidneys filter about 120-150 quarts of blood a day to eliminate waste from the body. There are about a million filtering units inside of the nephron inside of each kidney. The glomerulus inside of the nephron allows liquids to pass. It is supposed to prevent larger molecules like blood cells and protein from being eliminated. The tubule sends needed minerals and products back to the bloodstream. The urine is sent out of the kidney via the ureter.

At this point, as long as the ureters keep the urine moving, it heads to the bladder. It is held there for elimination. The nerves single the brain and the sphincter’s open and the urethra allows the urine to exit the body.

What Are The Components of Normal Urine?
Normal urine should contain water, urea, urochrome, salts, creatinine, byproducts of bile and ammonia. There should be no other components to urine. If there are, that means something is not functioning correctly in the system. It could be as simple as an infection, to as complex as a kidney malfunction.

What Happens When the Renal System Doesn’t Work Right?
There can be problems in any of the locations of the urinary system preventing it from working correctly.

Kidney Issues
Some types of kidney problems can indicate the development of chronic kidney disease. It’s important to get a diagnosis and treatment for any type of kidney problem as quickly as possible. Over time, chronic kidney problems can result in permanent damage or kidney failure.

Signs of Kidney Issues
Blood and protein in urine are warning signs of a kidney problem. Blood and protein are important and need to remain in your body. The kidneys should not be filtering these out.

Blood cells

Bloodwork can show early signs of kidney problems. The BUN, creatinine and GFR (glomerular filtration rate) can be out of range if there is a kidney issue. The BUN (or blood urea nitrogen) levels increase when the kidney isn’t functioning correctly. Urea should be filtered out by the kidneys. If the blood level is too high that means the kidneys aren’t removing it. The creatinine test goes along with BUN because creatinine is another waste product. It also should be removed by the kidneys. If left in the blood that could mean the kidneys aren’t functioning properly. The GFR tells the doctor the amount of kidney function. Ranging from a G1-5 – the higher the number the less kidney function.

Other Kidney Problems
These include things like kidney stones, kidney injuries, kidney pain and of course kidney infections. There are also autoimmune diseases that lead to kidney problems and kidney failure. Those include certain types of periodic fever conditions, lupus, and other autoimmune diseases.

Other Component Problems
The ureters can become obstructed or injured causing the urine to move freely from the kidneys to the bladder.

The bladder can malfunction as well. Urgent feelings of the need to urinate, frequent urination and loss of control of the bladder are common problems. The problems can be related to the nerves in the bladder or physical problems with the sphincters that open and close the bladder.

The urethra can develop problems as well. It can constrict at one end not allowing the urine to the leave the body, or become inflamed from infection. Both cause difficulty urinating.

The long-term outcome of a malfunction in the renal system is waste backing up in the body. Eventually, the body can be poisoned by the waste if it is not eliminated from the body.

Want to learn more about the renal system, its components or treatments, and physicians. Here are some simple and complex online sources. Depending on your comfort level of medical language you can check out each one.