Here's a wild one. A grown-up's body is made of about 30 trillion of its own cells. And every single day, about 330 billion of them get swapped out for brand-new ones. Not once a year. Not once a week. Every day!
But not every cell gets swapped out that fast. Some cells can last for years before they're replaced. And some cells, like ones in your brain and eyes, can last your whole life. Those are the long-timers of your body!
Here's a bonus wow. Grown-up men have about 36 trillion cells on average, and grown-up women have about 28 trillion. And on top of all those cells, a typical adult body also carries about 38 trillion bacteria. That's even more bacteria than human cells!
So here's a question to think about: if your body swaps out billions of cells every day, are you still the same you as yesterday?
