The Kidneys

The kidneys work by helping people to be able to get rid of waste in the body. The kidneys sit right beside the belly button, closer to the back and they are around the size of your fist.

Most people have two kidneys and the kidneys get blood from the heart.

While the heart pumps blood through the body, the blood also pumps from the heart into the kidneys and the kidneys help to filter the blood and gets rid of urine, that goes to the bladder until it is time to get rid of the urine.


The kidneys have arteries that go to the kidney and the arteries help to keep nutrients, electrolytes, proteins, amino acids and other important nutrients in the body.

The arteries also help to move oxygen, but they also bring waste such as extra nutrients that our body does not need.

Salt is one of these nutrients that our body does not need to keep and is filtered through the kidney.

Collecting Nutrients

The kidney helps to collect the nutrients from the arteries and then it also helps to get rid of waste so that it does not go into the vein.

When getting rid of these nutrients and extra stuff that is not needed in the body, the kidneys produce urine.

Capillary Beds

The kidney has two capillary beds, which are things that connect the artery to the vein.

It is used to bring oxygen in. The first capillary bed found in the kidney is called the vasa recta.

This gives oxygen to the kidneys. The other capillary is called peritubular capillaries, and this is responsible for collecting the nutrients that the kidneys filter.

Kidney Disease

The kidneys sometimes do not work the way that they should and when this happens, people sometimes get kidney disease.

Chronic kidney disease is when the filters in your kidney do not work the way that they are supposed to.

The kidneys are meant to separate the blood from extra fluid in the body and when this does not work, kidney disease is present.


People that have kidney diseases sometimes have to do dialysis and this is a process where a machine cleanses the blood and takes out the extra fluid, without the use of the kidneys.

People who have kidney failure can also get a kidney transplant.

Kidney stones happen when there is too much calcium in the lining of the kidney.

Not drinking enough water to cleanse the kidneys is one likely cause of kidney stones.

Facts About Kidneys

  • The kidneys can hold 22% of your body’s entire blood flow.
  • The kidney has millions of nephrons, and nephrons are tiny filters that help to catch the waste that the body does not need.
  • Fun fact! Kidneys are named kidney because they are shaped like kidney beans.
  • The kidney helps to balance the fluid that is in the body.
  • The kidneys can change a person’s blood pressure because the kidneys make a hormone that can make the arteries in the body smaller.
  • Kidneys help to make red blood cells.
  • Kidneys help to produce vitamin D that helps to make bones and teeth healthy.
  • Drinking 4-6 glasses of water per day can help keep your kidneys working hard.
  • Our body can still work well with only one kidney.
  • Healthy kidneys do not allow red blood cells to go into the urine.
  • Renal means “having to do with the kidneys”
  • Homeostasis is the work that the kidneys do when it balances the body fluids.

What Did You Learn?

  • What do the kidneys help the body do? The kidneys help the body to get rid of excess waste.
  • What form does the liquid waste come in? The liquid waste that the kidneys get rid of is urine.
  • How many capillary beds does the kidney have? The kidney has two capillary beds, the vasa recta and the peritubular.
  • What is a capillary bed? The capillary bed connects the vein to the artery.
  • What does the arteries do? The arteries try to help the kidneys get rid of extra waste and hold on to nutrients that the body does need.
  • How many kidneys are needed to live? People can live with one or with two kidneys and still have a normal functioning body.