Alyssa Moody

Boisture Block 2

9/13/17

Table of Contents

Introduction...3

Nature of Light...5

Structure of Visual System...11

How We See Color...17

The Nature of Sound...26

Structure of the Auditory System...31

How We Hear...36

Max and Ruby love to play together in the backyard.

They like to garden, play pretend, and build sandcastles.

All around them are trees, flowers, birds, and bees.

One day while Max and Ruby were making balloon animals, Ruby asked...

"Max, do you know how we can see the flowers, and how we know what color they are?

Max shakes his head no. Ruby thinks Max should know how we can do these things.

This is what your eye looks like from the side! Your eyes help you see everything around you.

Let's take a closer look at the different parts of your eye and how it works.

frequency and amplitude

Your eyes do something called transduction to tell your brain what you see; they take energy from the light all around you and make it into mail for your brain. Your brain opens the mail to know what you see.

This can happen, because light is like the ocean.

It moves in waves!

The light you see is a small slice of a big whole of colors, just like a slice of pizza.

The "pizza" is called the electromagnetic spectrum.

This is a big rainbow of light waves, that are long or short.

Wavelength/frequency - The space between the tip tops of each light wave. This is what makes hue, or the color of the wave.

Amplitude - The tallness of each wave. This is what controls the intensity of light, or how bright it is.

wavelength/freqeuncy

The longer the wave, the more red the hue.

The shorter the wave, the more violet the hue.

amplitude

The taller the wave, the duller the hue, or less bright.

The shorter the wave, the brighter the hue.

Max doesn't say a word.

"Good question, Max. How DOES light get all the way to our brain?" Asks Ruby.

But Max knew that Ruby already had the answer.

"First, let's say that I see this daffodil. Isn't it beautiful?" Says Ruby.

First, the light from the daffodil zooms into my eye.

The light very first comes through the cornea, the "see through" part of your eyes.

The light then comes to the lenses of the eyes, the curved, bendy part, behind the cornea. This helps your eyes see light easily. It flips to the side, and turns upside down before going to the next station, like a train.

Then, the light from the daffodil goes through the lens to the retina, the place in the back of my eye. This is where we see rods and cones.

Rods help us see black and white hues. Cones help us see colorful hues.

These are neurons, or cells, that send energy to the optic nerve, the stick-like thing that keeps your eye and brain touching each other.

When light comes to the rods and cones, signals are made. These wake up the bipolar cells, that just run over and wake up the ganglion cells, the things that come together to make the optic nerve. Think of it like bees waking up their neighbors!

wake up Jerry!

Zzzz

On your eye, you also have your pupil, the black part of your eye. This can open to let more light in your eye, or close for less.

And you have the iris, the colorful part of your eye. It controls how much your pupil opens or closes.

The optic nerve is kind of like grandma, because it has a blind spot!

The optic nerve's blind spot is the place

where it leaves the eyeball, but there are

no receptor cells hanging around.

Like Max and his friends sat on the rug at school this morning,

Cones are found around the fovea, a dent on the retina where cones are broken up, and usually go, just like how Max tends to sit in the same spot every day.

"Last but not least, Max, we have the optic chiasm. This is where our optic nerve goes into our brain from each eye, and cross over top each other. This helps both sides of our brain know what we see," Ruby explains finally.

The optic nerve sends messages, about what you're seeing, into the visual cortex of your brain. This is like the control center that tells your brain what you see, based on what your optic nerve tells it!

"But Ruby," Max says, "How do we really see colors? Tell me more!"

How We See Color

Cones work when they touch color

Rods work when they touch black and white.

Trichromatic Theory

This says that our retinas have receptors that pick up three colors: red, green, and blue.

When we mix these colors together, we get other colors!

for example: red + green = yellow

Opponent-Process Theory

Like everyone has a best friend, this tells us that each color in this theory comes with a partner. The groups are red/green, yellow/blue, and black/white. When you see one color, the other color can't work.

This causes us to see things called afterimages!

Afterimages are like when you look at the sun for a few seconds, and when you look away you see the color blue!

Please don't look at the sun if you haven't done this before, it will hurt you!