I’m going to answer Jen Alexander’s BIG question, "Do your organs grow with you?"

Well, Jen, the answer is yes, for the most part. They grow until you’re fully grown,

which is usually your late teens and early twenties. But it’s hard to generalize considering

you have almost 80 organs, which make up many different organ systems. So, I’m going to

explain the development of a few different organs for you today, including the heart,

the lungs, the liver, and the brain. Let’s get started!

Right after conception, a fetus’s heart takes up almost all of its midsection. Other

than that though, your heart is pretty much always around the same size as your fist at

the time. Even babies have hearts the size of their itty bitty fists. Then, it grows

with that person. Once they stop growing, their heart stops growing too. There are some

conditions that make the heart continue to grow after this point though. These include

high blood pressure and a leaky heart valve. Or love. But that's metaphorical.

Lungs start working after birth. At first, they’re filled with amniotic fluid. Then,

the baby takes their first breath and lungs start to do their job. Crying. A lot. Lungs

continue to grow until people are in the late teens or early twenties. This is why young

people smoking is such a concern -- their lungs don’t end up developing to the extent

and size they should.

The liver reaches its full size, of around 3 pounds, at the same time. The liver IS capable

of regenerating itself though which is why people are able to donate a piece of their

liver to another person. Or to a dog, maybe. Probably has never happened.

At birth, the brain is about 25% of the size it’ll reach, then it starts to grow fast.

By the time a child is 2-years-old, the brain is 80% of its adult size. It also stops growing

around your twenties. But, even when it has stopped growing, the brain continues to develop

in other ways until it’s around 25-years-old. And then we just all, just remain that smart.

We're just dumb until we die. No! Never stop learning.

Putting aside the liver’s ability to regenerate and the brain’s ability to continue to develop,

there’s really only two organs that will continue to grow until you die: your ears

and your nose. Six-year-olds have ears that are 90% fully grown. And that’s the case

for teenagers with their noses. But, still, a little elongation continues throughout life

thanks to cartilage growth and gravity. And lying.

Speaking of organs on our faces, there’s a common misconception that eyes don’t grow

at all after birth. In fact, they grow a little, but stop when you’re about 13-years-old.

Thanks for watching Mental Floss on YouTube, which is made by these regular organ sized

people. If you have a question of your own that you’d like answered, leave it below

in comments. And I will see you next week!