Kidneys 101

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Kidneys play an important role in filtering excess water and waste products from the blood. Located on either side of your spine below the rib cage, they filter about half a cup of blood every minute, creating one to two cups of urine every day. Kidneys also regulate pH, salt, and mineral levels in the blood. Muscles, nerves, and other tissues need proper acidic blood balance to function normally. Kidneys also make hormones that help regulate blood pressure, create red blood cells, and activate a form of vitamin D that helps the body take in calcium for building bones. Kidneys are made up of about a million tiny filters called nephrons. Within the nephron, there are two parts: the glomerulus and the tubule. When blood enters the kidney, the glomerulus first filters the blood, then the tubule collects minerals and nutrients that the body needs and puts them back into the bloodstream. The leftover fluid and toxins are excreted as urine.

Working of Kidney

Diagram Courtesy of NIH NIDDK

Humans cannot live without a functional kidney. However, we actually have more kidney capacity than we need to sustain life. Humans have two kidney organs and a single kidney operating at only 75% capacity can maintain a fully functional human body. This means that it is very possible to live with only one kidney. In fact, when the human body has only one kidney, that kidney adjusts to filter the same amount of blood two kidneys would. In that situation, the nephrons in the singular kidney would increase in size, and the entire kidney would eventually reach the weight of two kidneys, weighing around a pound. Scientists are not certain why humans evolved with two kidneys. Some speculate that symmetry in the body allows it to move more easily or that having two copies of organs help support the spinal cord and central nervous system. Whatever the reason may be, kidneys are an important enough organ in the human body that most people have two of them.

There are many simple steps you can take to keep your kidneys healthy and functioning. Many factors that contribute to overall health also apply to kidney health. Drinking water and staying hydrated is important because kidneys need water to flush out toxins. Most people should aim for 1.5 to 2 liters of water a day. High blood pressure can also harm your kidneys, as can obesity. Maintaining a diet that is low in sodium and processed meat as well as limiting caffeine and alcohol consumption can help with optimal kidney health. Regular exercise also helps prevent high blood pressure, and in turn, keeps internal organs functioning. Finally, certain over the counter medications such as ibuprofen and naproxen can cause kidney damage if taken on a daily basis. From flushing out toxins to getting rid of excess water, kidneys are vital to our survival!