Can you guess what the fastest moving muscles in the human body are?

Here's a hint, they move in the blink of an eye.

Now what do you think?

Yup, you guessed it, the six muscles that help you blink your eyes are the fastest moving muscles in your body.

Let's go on a sightseeing field trip and explore the inner workings of the human eye.

The human eye is located inside a hollow area of the skull called the eye socket.

The eyelid is what protects the front part of the eye.

It does so by blinking.

Blinking is what helps keep your eyes clean by keeping dirt and substances out of the eye.

Blinking also prevents the eyes from getting too dry.

Lacrimal glands are responsible for making tears, which also help keep your eyes clean.

Here is an interesting fact about blinking.

It can be both voluntary, meaning you choose to do it, and involuntary, which means it happens automatically as a reflex.

This reflex happens when the light is too bright or if you need to shut your eyes quickly for protection.

Have you ever looked in the mirror and wondered what the white part of your eye is called?

It is called the sclera.

The sclera is the outer covering of your eyeball and is made of super strong material.

It also has blood vessels, which helps a blood flow to your eyeball.

Next up, the cornea.

The cornea is a transparent dome that is located in the front of the colorful part of your eye.

It helps the eye focus when it's exposed to light.

Think of it this way.

The cornea is kind of like a window that your eye sees through.

Pretty cool, right?

Another important part of the human eye is the anterior chamber.

It is the space between the cornea and the iris and is filled with a transparent fluid that helps keep the eye healthy.

What color are your eyes?

Did you know that the colorful part of your eye is called the iris?

And what about the black circle in the middle?

That's right.

It is the pupil.

The iris and the pupil work together in an interesting way.

Light travels through the iris before arriving at the pupil.

Here is an interesting fact.

There are muscles that are attached to the iris that actually change its shape.

This is important because this process is what controls the amount of light that goes through the pupil.

The pupil is what lets light enter your eye.

It adjusts to the amount of light by opening wider when you need more light and shrinks when there is plenty of light available.

And here we thought eyes were just nice to look at.

So what happens after light enters your eye through the pupil?

It hits the transparent lens located just behind the iris.

Like all lenses, it is usually used to focus light and it focuses light rays all the way to the back of the eyeball to a part called the retina.

The retina is home to millions of cells that are light-sensitive.

These cells are called rods and cones.

Rods see in black, white, and gray, as well as can detect the differences in colors, and they pass along the shapes of what you see.

On the other hand, there are three different kinds of cones, and these cones are most helpful when you experience brighter light.

Cones also help you to see all different kinds of colors and their shades.

In short, the retina takes all of the gathered light in your eye and uses rods and cones to change it to signals that are sent to the brain.

This is done via the optic nerve.

The optic nerve carries all of this information to the brain, and that is how the brain is able to tell you what you are seeing.

Here is an interesting fact.

By the time an image reaches the retina, it is actually upside down.

This is because the image is refracted, or bent, as it moves through the different parts of the eye.

But when the optic nerve carries this information to the brain, the image is flipped right side up.

This happens so fast that you cannot even tell it is happening.

There are also a couple more parts of the eye that are important.

First, the ciliary muscle, which changes the shape of the lens of your eye when you need to see things close up, far away, or out of the corners of your eyes.

Last is the vitreous body, which is the largest part of the eye.

It takes up about two-thirds of the volume of the eye, and gives the eye its shape.

We knew that the eyeballs were cool, but who knew that they were this complex?

We have learned a ton of new information about the human eye.

Let's see what you remember.

Fill in the blank.

The part of the eye that sends signals to the brain is called the blank nerve.

Optic nerve.

True or false.

The retina has two types of cells, called rods and cones.

True.

Which part of the eye is the colorful part?

The iris.

Great work, visionaries!

The eyes are an extremely important part of your body, and should always be taken care of.

The next time you are outside, put a pair of shades to protect those pretty peepers from the sun's rays.

And think about all of the different parts of your eye working together to help you see everything around you.

Hope you had fun learning with us!

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