Kidney · Visual journey

Your kidneys take back what you need.

Just below your rib cage, one on each side of your spine, your kidneys process your blood. How do they separate what you need from what ends up in your urine?

Scroll to step inside the kidney ↓

Inside the kidney

Blood goes back. Urine moves on.

Blood comes in through the red artery and leaves through the blue vein. Urine flows down the ureter, the pale tube that runs from the kidney to the bladder.

A microscopic unit

First it filters. Then it takes back what’s useful.

The nephron is one of the kidney’s working units. It starts at the glomerulus, a tiny ball of blood vessels that filters the blood. Next comes the tubule, a small tube that returns water and useful substances to the blood.

After the tubule takes back what your body needs, the fluid that’s left becomes urine.

Now, real tissue

Here’s that ball of vessels.

In the center, you can see the glomerulus. Its vessels let water and small molecules pass through, while blood cells and most proteins stay in the blood. Tubules surround it.