Kidney facts for kids

Quick facts for kids Kidneys
Posterior view of kidneys and their external vasculature, with adjacent posterior structures labelled.
Left: location of kidneys within the body. Right: gross anatomical structures within the kidney (midsagittal cut, left kidney).
Latin	Ren
System	Urinary system and endocrine system
Artery	Renal artery
Vein	Renal vein
Nerve	Renal plexus

Your kidneys are two organs in your abdomen (the area of your belly) that are shaped like beans. They make urine and are an important part of your urinary system. When doctors talk about kidneys, they often use the word renal. For example, renal failure means the kidneys are sick and not working properly.

How Your Kidneys Work

Inside a kidney

Your kidneys do many important jobs to keep your body healthy. One key job is making special chemicals called hormones. Two very important hormones they make are erythropoietin and renin.

Erythropoietin and Red Blood Cells

Erythropoietin is made by your kidneys if they sense there isn't enough oxygen in them. This hormone then tells your bone marrow (the spongy part inside your bones) to create more red blood cells. More red blood cells mean more oxygen can be carried around in your blood.

Renin and Blood Pressure

Renin is another hormone made by your kidneys. It's released if your blood pressure is too low, or if you don't have enough blood or salts in your blood. Renin helps to make your blood vessels narrower, which can raise blood pressure. It also tells your adrenal gland (a small gland near your kidney) to make aldosterone. Aldosterone helps your kidneys save important salts. Renin can also make you feel thirsty, encouraging you to drink more. All these actions help to bring your blood pressure back up to a healthy level.

Keeping Your Body Balanced

The most important job of your kidneys is to maintain homeostasis. This is a fancy word that means keeping a stable and balanced environment inside your body. Your body needs to have just the right amount of water, salt, and acid in your blood. Your kidneys work constantly to keep these things balanced.

If you drink too much water, your kidneys will put more water into your urine to get rid of the extra. If you don't have enough water, like when you are dehydrated, your kidneys will save water and make less urine. This is why your urine might look darker when you haven't had enough to drink.

Kidney Diseases

A camel kidney

There are many different types of kidney diseases. When someone has a kidney disease, their kidneys can't work perfectly, but they might still work a little bit. Sometimes, people can have mild kidney problems and not even notice any symptoms. As long as the problem doesn't get worse, they might not know they have it.

Severe kidney failure means the kidneys are working very poorly, or not at all. People with severe kidney failure always have symptoms and need special medical care.

Replacing Kidney Function

If someone has severe kidney failure, they cannot live without help. There are two main ways to replace the work of the kidneys:

• Dialysis: This is a medical treatment where doctors use a special machine and medicines to clean the blood and do the jobs your kidneys normally would.
• Transplantation: A better way to replace the kidneys' work is to give the person a healthy kidney from another person. This is called a kidney transplant.

Kidney transplants are the most common type of organ transplant. This is because most people have two kidneys, but you only need one healthy kidney to live. This means that people who are alive can sometimes donate one of their kidneys to someone who needs it.

Images for kids

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  Image showing the human trunk with positions of the organs. The kidneys are at the vertebral level of T12 to L3.

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  The nephron, shown here, is the functional unit of the kidneys. Its parts are labelled except the (gray) connecting tubule located after the (dark red) distal convoluted tubule and before the large (gray) collecting duct (mislabeled collection duct).

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  Secretion and reabsorption of various substances throughout the nephron

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  A depiction of peritoneal dialysis.

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  Hökarpanna [sv], Swedish pork and kidney stew

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  Normal adult right kidney as seen on abdominal ultrasound with a pole to pole measurement of 9.34 cm.

See also

In Spanish: Riñón para niños