Vision is considered the dominant sense of humans but it can be tricked!! Optical illusions use combinations of colors, lights, or particular patterns and perspective that can really trick the brain. Other illusions produce ghost effects or afterimages, taking advantage of the physiology of human vision. What your eyes see isn't always what your brain understands: there can be a disconnect between sensation and perception. So get ready to check your visual perception with this fun challenge!
Your ears are in charge of collecting the sounds around you, processing them, and sending sound signals to your brain. They also help you keep your balance.
The ear is made up of three different sections: the outer ear, the middle ear, and the inner ear. These parts all work together so you can hear and process sounds.
The Outer Ear:
The outer ear is called the pinna or auricle, which collects sounds. The outer ear also includes the ear canal, where earwax is produced. Earwax protects the canal and contains chemicals that fight off infections that could hurt the skin inside the ear canal. It also collects dirt to help keep the ear canal clean.
The Middle Ear:
After sound waves enter the outer ear, they travel through the ear canal and make their way to the middle ear. The middle ear's main job is to take those sound waves and turn them into vibrations that are delivered to the inner ear. To do this, it needs the eardrum, which is a thin piece of skin stretched tight like a drum.
The eardrum separates the outer ear from the middle ear and the ossicles: the three tiniest, most delicate bones in your body. They include:
the hammer , which is attached to the eardrum.
the anvil, which is attached to the hammer.
the stirrup, the smallest bone in the body, which is attached to the anvil.
When sound waves reach the eardrum, they cause the eardrum to vibrate. When the eardrum vibrates, it moves the tiny ossicles — from the hammer to the anvil and then to the stirrup. These bones help sound move along on its journey into the inner ear.
The Inner Ear: Nerve Signals Start Here
Sound comes into the inner ear as vibrations and enters the cochlea, a small, curled tube in the inner ear. The cochlea is filled with liquid, which is set into motion, like a wave, when the ossicles vibrate.
The cochlea is also lined with tiny cells covered in tiny hairs. When sound reaches the cochlea, the vibrations (sound) cause the hairs on the cells to move, creating nerve signals that go through the auditory nerve to the brain, which interprets them so you can hear.
How hearing works
Balance
Ears keep you balanced, too. In the inner ear, there are three small loops above the cochlea called semicircular canals, which are filled with liquid and have thousands of microscopic hairs.
When you move your head, the liquid in the semicircular canals moves too. The liquid moves the tiny hairs, which send a nerve message to your brain about the position of your head. In less than a second, your brain sends messages to the right muscles so that you keep your balance.
Don't forget to look after your ears!
Your ears take care of you, so take care of them. Protect your hearing by wearing earplugs at loud music concerts and around noisy machinery. Keep the volume down on your stereo, especially if you're in the car or wearing headphones. And one last thing — don't go poking around in your ears, even with cotton swabs. (Information taken and adapted from: https://kidshealth.org)
Your eyes take in tons of information about the world around you — shapes, colors, movements, and more. Then they send the information to your brain for processing so the brain knows what's going on outside of your body.
The eye is about as big as a ping-pong ball and sits in a little hollow area in the skull called eye socket. The eyelid protects the front part of the eye and helps keep the eye clean and moist by opening and shutting several times a minute. This is called blinking. The eyelid also has great reflexes (automatic body responses) that protect the eye. When you step into bright light, for example, the eyelids squeeze together tightly to protect your eyes until they can adjust to the light. The eyelashes work with the eyelids to keep dirt and other unwanted stuff out of your eyes.
The white part of the eyeball is called the sclera, which is made of a tough material that covers most of the eyeball. You can see tiny blood vessels here as well.
The cornea is in front of the colored part of the eye. The cornea helps the eye focus as light makes its way through. Like clear glass, the cornea gives your eye a clear window to view the world through.
The iris is the colorful part of the eye. When we say a person has blue eyes, we really mean the person has blue irises! The iris has muscles attached to it that change its shape. This allows the iris to control how much light goes through the pupil
The pupil is the black circle in the center of the iris, which is really an opening in the iris, and it lets light enter the eye. The pupils will get smaller when a lot of light shines near them and they'll open wider when there is little light.
After light enters the pupil, it hits the lens, which is clear and colourless. The lens' job is to focus light rays on the back of the eyeball — a part called the retina.
The lens actually changes shape inside your eye: when you look at things up close, the lens becomes thicker to focus the correct image onto the retina; but when you look at things far away, the lens becomes thinner.
Your retina is in the very back of the eye. It holds millions of cells that are sensitive to light. The retina takes the light the eye receives and changes it into nerve signals so the brain can understand what the eye is seeing. The retina uses special cells called rods and cones to process light:
- Rods see in black, white, and shades of gray and tell us the form or shape that something has. Rods can't tell the difference between colors, but they are super-sensitive, allowing us to see when it's very dark.
- Cones see color and they need more light than rods to work well. Cones are most helpful in normal or bright light.
Sometimes someone's eyeball shape makes it difficult for the cornea, lens, and retina to work perfectly as a team. When this happens, some of what the person sees will be out of focus.To correct this blurry vision, many people wear glasses. Glasses help the eyes focus images correctly on the retina and allow someone to see clearly. As adults get older, their eyes lose the ability to focus well and they often need glasses to see things up close or far away.
Think of the optic nerve as the great messenger in the back of your eye. The rods and cones of the retina change the colors and shapes you see into millions of nerve messages. Then, the optic nerve carries those messages from the eye to the brain, which interprets the information.
Above the outer corner of each eye are the lacrimalglands, which make tears. Every time you blink your eye, a tiny bit of tear fluid comes out of your upper eyelid. It helps wash away germs, dust, or other particles that don't belong in your eye. Tears also keep your eye from drying out. Then the fluid drains out of your eye by going into the lacrimal duct (this is also called the tear duct). Your eyes sometimes make more tear fluid than normal to protect themselves. This may have happened to you if you've been poked in the eye, if you've been in a dusty or smoking area, or if you've been near someone who's cutting onions. And how about the last time you felt sad, scared, or upset? Your eyes got a message from your brain to make you cry, and the lacrimal glands made many, many tears.
Your eyes do some great things for you, so take these steps to protect them:
Wear protective goggles in classes where debris or chemicals could go flying, such as wood shop, metal shop, science lab, or art.
Wear eye protection when playing hockey, skiing, or other sports that could injure your eyes.
Wear sunglasses. Too much light can damage your eyes and cause vision problems later in life. For instance, a lens could get cloudy, causing a cataract, which prevents light from reaching the retina and makes it difficult to see.
Keep a balanced diet, which includes vitamin A (carrots).
Rest your eyes regularly when you read, watch TV or use a computer.
Go to the ophthalmologist regularly to have your eyesight checked.
(Information taken and adapted from: https://kidshealth.org)
Here you have some videos to learn more about your sight:
To begin to understand what smell is we must talk about the organ responsible for this sense: the nose.
The nose is a protuberance located between the eyes and the mouth. It is part of our respiratory system, allowing us to breathe in and out. In addition to breathing, the nose allows different odors to enter from our surroundings.
THE PROCESS OF SMELL
1. Molecules in the air reach the nostrils by breathing.
2. Specialized receptor cells called olfactory receptor neurons detect the odor.
3. The olfactory receptors transmit the information to the olfactory nerve, which is located at the back of the nose.
4. The olfactory nerve sends the information to the brain and the brain interprets the information as smell.
INTERESTING FACTS
People can detect at least one trillion distinct smells.
Olfactory cells are renewed every 30 to 60 days.
Women have a better sense of smell than men.
Dogs have nearly 44 times more olfactory cells than humans .
Each human being has their own distinct odor.
Our sense of smell peaks during our late teens, when we are around 18 or 19 years old.
Do you want to learn more about the sense of smell? Visit this website!
NEURONSare the cells of the nervous system. They have different parts with different functions:
-Cell body: it controls the neuron and creates nerve impulses.
-Dendrites: specialized projections that bring information to the cell the body.
-Axon: specialized projection that takes away information from the cell body.
NEURONS create electrical signals called nerve impulses to transmit messages from one cell to the next. The information goes from dendrites to axon in a neuron. There is a space between neurons called synapse and the nerve impulse needs chemicals called neurotransmitters to pass this gap between one neuron's axon and reach the next neuron's dendrites, where it becomes an electrical signal again.
(Pay attention: this is not explained correctly in your textbook!)
3D Models of Neurons
NEURON SONG
(from http://ihaveago.com)
Verse 1 -
A neuron is a cell of scientific fascination,
They receive, process and transmit information,
They allow us to think, solve problems and grow,
To learn the things we thought we could never know.
Chorus -
My abilities can be developed
With dedication and effort
When I find the right strategy
The one that works best for me.
Verse 2 -
Our brains have billions of neurons in a busy constellation,
Connected by branches in a network formation,
They fire in patterns, electrically,
Creating every feeling, thought and memory.
(Chorus)
Verse 3 -
Whenever I struggle, make mistakes and corrections,
I’m creating and strengthening my neuron connections.
Stimulating my brain and making it grow,
Making room for all the new amazing things I know.
The NERVOUS SYSTEM is the system
that receives all the information captured by the senses, interprets it and
responds or reacts to each situation.
It has special cells called
NEURONS and it is divided into two parts:
1. The Central Nervous System
2. The Peripheral Nervous System
1. Central nervous system:
the brain and the spinal cord.
A. The BRAIN is the most important organ
in the nervous system and the main control centre of your body, like a
computer. It has three parts:
FUNCTION
a. Cerebrum
It controls intelligence, memory,
personality, emotions, speech and voluntary movements (reading, jumping,
etc.) It has different areas or lobes with different functions.
b. Cerebellum
Balance, movement and coordination
c. Brainstem
It controls involuntary movements
(breathing, heart beat, blinking of our eyes, etc.) It links the brain and the spinal cord.
B. The SPINAL CORD
The
spinal cord is made up of nerve tissue forming
a long, thick tube within our spinal column. It is almost like a highway connecting the brain to all
the bodies’ nerves. The spinal cord is responsible for all the reflexes, like
when you touch something very hot and you take your hand away instinctively,
without even thinking.
2. Peripheral nervous system:
It is a set
of NERVES which travel around our body. There are two types of nerves:
a. Sensory nerves: carry information received by the five senses to the brain.
b. Motor nerves: transmit the brain’s responses to the muscles, joints and skin, which results in movement or a physical reactions like sweating.
