What is their role?
Most of the time, as long as it’s doing what it is supposed to, you don’t think about how your body functions. You probably know that your kidneys make urine, but how does it do this? Where does the items that make up your urine come from? Why is this process important?
The kidneys have a variety of functions within your body, such as making hormones that help to control blood pressure, make new red blood cells and keep your bones strong, but the function that you are probably most familiar with is their ability to make urine. It does this by filtering acid (produced by your cells), toxins, waste and extra fluid from your blood and turning it into urine. Your kidneys can filter about a half of cup of blood a minute, which is about 150 quarts of blood a day and this filtration makes 1-2 quarts of urine every day. This filtration process helps your body to maintain a balance between water, salts and minerals. This balance is what allows your nerves, muscles and other tissues to function properly.
Your body has two kidneys, which are bean-shaped organs that are located just below your rib cage on each side of your spine. The three main parts are the renal cortex, renal medulla and renal pelvis. The renal cortex is the outer part of your kidney and it is surrounded on the outer edges by the renal capsule (layer of fatty tissue). Together the protect the inner structures of the kidney. The glomeruli and convoluted tubules are inside this part of your kidney. The renal medulla is the smooth, inner tissue of the kidney and contains the loops of Henle and renal pyramids (small structures that have strings of nephrons and tubules). The renal pelvis is a funnel-shaped area in the inmost part of the kidney. It holds the calyces and hilum. The hilum is a small opening where the kidney curves inward and allows the renal artery to bring oxygenated blood to the kidney to be filtered and the renal vein to take filtered blood from the kidneys.
In order to do its job, there are several structures on the inside of your kidney. The blood that needs to be filtered arrives at your kidneys via the renal arteries. Once it is in a kidney, it starts to go through a filtering unit called a nephron. Both kidneys have about a million of nephrons. Each nephron is broken down into several components that work together to filter the blood. The first part is called the renal corpuscle and it is made up of two structures. The glomerulus is a group of tiny blood vessels (capillaries) that allow smaller molecules, wastes and fluid to pass through from the blood vessel and keep large molecules, like proteins and blood cells, in the blood vessel. The items that are able to pass through glomerulus move on to the Bowman capsule and then into the renal tubules. Renal tubules are a group of tubes that began at the Bowman capsule and end at collecting ducts. Alongside each one is a tiny blood vessel that reabsorbs certain substances as the filtered fluid moves through the three parts of each individual tubule. The proximal convoluted tubule filters water, sodium and glucose back into your blood. The loop of Henle puts potassium, chloride and sodium from the fluid back into your blood. The distal convoluted tubule releases more sodium into your blood but retains potassium and acid in the fluid. By the time the filtered fluid reaches the collecting ducts at the end of the distal convoluted tubule, it is diluted and filled with urea (byproduct of protein metabolism). From the collecting ducts, the fluid moves into the calyces, which are small cup-shaped spaces that collect the fluid from multiple collecting ducts. Each kidney has 6 to 10 calyces. From here the fluid moves past the hilum into the ureter (the tube that connects your kidney to your bladder). Once in your bladder, the urine builds up until your bladder sends the signal that you need to urinate.
Your kidneys are vulnerable to having a wide variety of problems because of the function of removing toxins and waste from your blood. Some common problems are kidney stones and urinary tract infections. There are several other very serious conditions. Azotemia is when you have high levels of nitrogen-containing compounds, such as urea, creatinine, various body waste compounds, and other nitrogen-rich compounds, in your blood because your kidneys are unable to filter them out. Acute nephritis is when your kidneys suddenly become inflamed and has several causes. Glomerulonephritis is inflammation of the tiny filters in your kidneys, also known as glomeruli. Pyelonephritis is when inflammation from a urinary tract infection reaches the renal pelvis of the kidney. Caliectasis is when the calyces become dilated and swollen with extra fluid. It’s usually caused by another condition that affects the kidneys, like a urinary tract infection. Uremia occurs when your kidneys become damaged and the toxins (urea) that your kidneys normally send out in your urine end up in your bloodstream. Hydronephrosis is swelling of a kidney due to a build-up of urine because the urine cannot drain from the kidney to the bladder due a blockage or obstruction. Acidosis is a condition in which there is too much acid in the body fluids and this can occur if your kidneys aren’t filtering the acid out sufficiently. Kidney cysts are fluid-filled sacs that grow in your kidneys. You might have a single cyst on one kidney or many cysts on both kidneys. Polycystic kidney disease is when clusters of cysts develop primarily within your kidneys causing them to enlarge and lose function over time. Nephrotic syndrome is a kidney disorder that causes your body to excrete too much protein in your urine because of damage to the clusters of small blood vessels in your kidneys that filter waste and excess water from your blood. Kidney failure occurs when the kidneys no longer function well enough to do their job. Chronic kidney disease (chronic kidney failure) is the gradual loss of kidney function over time.
Symptoms for kidney conditions vary, but some of the most common are blood in urine, foamy urine, painful urination, increased or decreased urination, dry/itchy skin, foot/ankle swelling, trouble sleeping, fatigue, inability to concentrate, puffiness around your eyes, reduced appetite and muscle cramps. If your kidney condition is serious enough, you could end up needing dialysis. This is the medical process of removing the excess water, waste and toxins from the blood because your kidneys have lost the ability to perform these functions. For some conditions, this is a temporary need, but for others, this is a permanent part of managing their condition. In order for dialysis to be effective at replacing the function of your kidneys, it needs to be done several times a week and each session lasts several hours each time. This is why it is important to protect the health of your kidneys.
Healthy Kidney Tips
In order to keep your kidneys functioning healthy, there are several things that you can do. The first thing is to avoid certain conditions that put you at increased risk for kidney problems, such as diabetes, obesity and high blood pressure. Eating a large amount of salty foods can alter the balance of minerals in your body, which can make it harder for your kidneys to do their job. So, avoiding processed foods and not adding lots of salt to food is essential. By eating fresh fruits and vegetables, lean cuts of meats and unsalted nuts, you can help your kidneys function better. Staying hydrated with plenty of water is also important because it allows your kidneys to help remove toxins from your bloodstream. Since high blood pressure is a risk factor for developing a variety of kidney problems, it is vital to maintain a healthy blood pressure. A good way to do this is by exercising…even 20 minutes a day can be beneficial. Another important thing to consider is the use of medications that can cause kidney damage. Some of these medications include over-the-counter nonsteroidal anti-inflammatory, like ibuprofen. It is fine to take these medications occasionally if you need them for pain relief, but not to taking them in large quantities or daily.
Your kidneys are a vital part of your body and it is essential to keep them functioning appropriately. By taking care of them, they will take care of you. If you have any questions about your kidneys and how they function, please speak with your doctor. If you would like more information, please visit the National Institute of Diabetes and Digestive and Kidney Diseases page on kidney function at https://www.niddk.nih.gov/health-information/kidney-disease/kidneys-how-they-work