ELI5: Nephrons

A nephron is a tiny, microscopic filter inside your kidneys that cleans your blood and turns waste into pee.

Think of your body like a busy house that creates a lot of trash every day. When you eat, drink, and play, your body uses what it needs and leaves behind leftovers in your bloodstream. If that trash piled up, you would get sick.

This is where your kidneys come in, and they do their job using about one million tiny cleaning workers called nephrons.

Here is how a nephron works, just like sorting through your toys and trash:

• Catching everything: Blood rushes into the nephron, which has a tiny strainer called the glomerulus. This strainer catches extra water, salts, and waste, but keeps your important blood cells safe inside your body.
• Saving the good stuff: Next, the liquid travels down a winding little slide called a tubule. The nephron acts like a smart recycling machine here, quickly grabbing back useful things like clean water and nutrients to return them to your blood.
• Throwing out the junk: Whatever is left over—the real trash and extra fluid—keeps moving to the end of the slide.

Just like running a kitchen water filter to get clean drinking water, your nephrons run non-stop all day and night to keep your blood fresh, healthy, and clean.