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The Human Eye
Transcript of The Human Eye
The Eye and The Camera
The Human Eye
~The power of sight
~Parts of the Eye
Cornea: The see-through layer that covers the Iris and Pupil. Its convex shape helps focus light on the Retina.
Iris: The coloured ring behind the Cornea.
It makes the Pupil large when light is dim and small when light is bright.
Aqueous Humour: The transparent fluid
between the Lens and Cornea.
Vitreous Humour: The jelly-like fluid filling the
inside of the eye, between the Lens and
Pupil: The hole in the Iris that
light passes through to reach the Retina.
Ciliary Muscle: Controls the thickness (shape)
of the Lens. Allows you to see near
and far objects.
Lens: A clear convex shape, behind
the Iris. It helps focus light that enters
the eye on the Retina.
Sclera: The white outside part of the eye.
It attaches to the Cornea and protects the
inside of the eye.
Retina: A thin membrane lining the inside
of the eye. It is where the image is made
and changed into Nerve Signal.
Optic Nerve: Carries Nerve Signals from the Retina to the Brain.
Did you know...
The convex lens of the eye, refracts and inverts (flips it upside down) the image in the eye.
The brain (Occipital Lobe) flips this image around.
The eye is the image creating organ of sight.
It is light sensitive.
It is almost spherical (circular).
There are usually two.
Eyes are most common in Vertebrates*.
The eyeballs are found in the Bony Orbit of the Skull.
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Light comes from a light source, or is reflected off an object. This enters the Cornea.
Light is Refracted in the Cornea.
The Iris expands and shrinks to let the right amount of light in. This makes the Pupil change size.
Light then passes through the pupil.
The Ciliary Muscles are attached to the Lens. They stretch and shrink the Lens. This lets our eyes bring the object into focus.
In the Lens the light is Refracted a second time.
The Refraction inverts and flips the image.
(Look closely at the path of light)
The image / light reaches the Retina.
The Optic Nerve transmits the Nerve Signals received from the Retina to the Brain.
The Nerve Signals are sent to the Visual Cortex in the back of the Brain. This is where the image is flipped back to "normal" and received.
To understand how we see colour, we need to look closer at the Retina.
The Retina is made up of specialized cells called Photoreceptors.
These are called Rods and Cones.
-There are 120 Million Rods
in the Retina.
-Are sensitive to Light/Dark,
Shape, and Movement.
-There are 6 Million Cones
in the Retina.
-Are sensitive to Colour.
-3 Colour Receptors:
What affects our perception of colour?
The amount of light present.
When the Rods and Cones in your
eyes tire it can take around 7
minutes to adjust to changes in
light. This can make colours appear different from what they are.
Not everyone's Cones are in working order.
Sometimes Cones in the Retina are weak or do not develop fully. This can lead to Colour Blindness.
Did you know...
Dogs are considered Colour Blind.
But some believe they can see hues
of yellow and blue.
~Parts of a Camera
~Path of Light
Shutter Release: The button on top of the Camera that opens the Shutter to expose the film. This controls the amount of time light is allowed inside.
Prism: A Pentaprism (Pentagon shaped). Flips the inverted image to let the Photographer see the actual image through the Viewfinder (where you look).
Aperture: Controls the size of the Diaphragm. Lets light in the Camera.
Diaphragm: A thin disc inside the Lens Structure. It changes shape to let a specific amount of light in. The size of the hole in the Diaphragm is based on the Aperture setting.
Film: A flexible plastic material that is sensitive to light. The image is imprinted on the chemical layer of the film, when light enters the camera. It is also called the Recording Medium. Digital Cameras use an Electronic Detector instead of Film.
Shutter Curtain: A layered plastic cover that is controlled by the Shutter Release. This Curtain-like part opens and closes to let light hit the Film
Mirror: Reflects the light that passes through the Lens onto the Prism. In some Cameras the Mirror moves instead of having a Shutter Curtain.
Lens System: A structure made up of multiple lenses. They can be concave and convex. Light Refracts and inverts the image. The Lens System lets you zoom in and focus on the object you are Photographing.
Lens Cap: A small lid that protects the Lens of the Camera, from dust, dirt and scratches.
Light comes from a light source or is Reflected off an object. This enters the Lens System.
Light is Refracted in the Lens System.
Can you guess what happens to the image?
The type of Lenses inside the Lens System decides the level of zoom and focus achieved. It is made of concave and convex lenses. Light is Refracted and the image is inverted
The Aperture and Diaphragm expand and shrink to let the right amount of light in. The Diaphragm changes size.
The Shutter Release controls how long the Shutter Curtain exposes film to light.
The Mirror usually moves with the Shutter Curtain. This causes the light to split.
When the Shutter Curtain is open the light reacts with the film and chemically creates the image.
The light enters and reflects inside the Prism. This Flips the image back to "normal" (as we see it).
Lab Safety Rules
***Any Unsafe Behaviour will result in the removal of your Lab Privileges. ***
***Meaning you will not continue with the Lab and Dissection.***
1) Follow all verbal and written instructions carefully.
2) If you do not understand part of an instruction. Ask.
3) Wait to touch any equipment or other materials in the Lab Stations until you are instructed to do so.
4) Do not eat food, drink beverages, or chew gum in the classroom.
5) Be prepared for your lab. Read all procedures before starting.
6) Horseplay, practical jokes, or pranks can be extremely dangerous. Common sense is big.
7) Once you enter the Lab your Lab Station is your area. You should not leave your desk unless you are asked by a teacher.
8) Keep aisles clear. Push your chair under your desk when not in use.
13) We will be using scalpels and very sharp instruments. You will not need to carry these around, so don’t.
14) Always cut away from your body. Use the dissection tray instead of your hands to cut against. Excessive force is not needed.
15) If an instrument falls, let it. Hold these instruments by the handles only. Remember these are tools, not toys.
16) Report ANY accident or injury (no matter how small) to the instructor immediately.
17) Lab Stations should cleaned and left as you found them.
9) Keep hands away from your face, eyes and mouth when using specimens.
10) Wear disposable gloves and goggles during dissection. Wash your hands with soap and water after.
11) Long hair should be tied back. Avoid wearing loose clothing and dangling jewelry.
12) Know the location of classroom safety equipment, first aid and fire exits.
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