LAB TEST NOTES and the EYE Flashcards
What is the eye?
The eye is the receptor organ for visible light waves.
Describe the process that occurs in the eye.
Eye receives a stimulus - Light
Eye transforms light into nerve impulse
Nerve impulse is carried by the optic nerve and cranial nerves
Light enters the place in the brain responsible for visual processing
What is the sclera?
The external membrane of the eye, white of the eye
Helps the eye hold its shape.
Acts as protection
What is the cornea?
Transparent layer.
Lets light through.
Bulges out of the front of the eye.
What is the choroid?
Dark brown
Many layers of blood vessels
Supplies the eye with blood, oxygen, and nutrients
What is the iris?
Choroid becomes the iris in the front of the eye
Made of muscle that contracts to close the pupil when exposed to too much light.
Seperate muscles contract ton open the pupil when there is not enough light.
What is the lens?
Located behind the iris
Biconvex shape
Flexible
thick - close
thin - far
Lens brings images to focus on the retina.
What is the aqueous humour?
Liquid part of the eye
Mostly water
Acts as protection
Provides nutrients and oxygen
Eliminates waste
What is the vitreous humour?
Clear gelatinous liquid
Back of the eye
Exerts pressure on the eye to help it keep its shape and hold the retina and lens in place.
Eliminates waste
Provides nutrients and oxygen
What is the retina?
Remember r and c
Membrane composed of receptor cells that are sensitive to light
Converts light inton nerve impulse using rods and cones
rods - shape
cones - colour
Objective
What are you being asked to do? Refer to the context.
Variables
Independent - causes changes
Dependent - reacts to independent
Hypothesis
If–independent–then–depenedent–because—explanation
Materials
Bullet points
Good vocabulary
Procedure
- No personal pronouns
- starts with a verb
- no data! just steps
- step-by-step, numerical order
- detailed
- don’t say ‘record results’, be specific (temp. conductivity, time, voltage, colour, etc.)
- Vocabulary
- Materials
Data and results
Titles, units and calculations
Analysis
connect theory to data
answer question and refer to context
Conclusion
Answer the question!
Relate to context!
Refraction
Refraction is a phenomenon by which light rays deviate when they pass from one medium to another with a different density. Light deviates from its path because it changes speed when it enters a different medium.
When a light ray hits a different material
it is called an incident ray
When a ray penetrates a different material,
it is refracted (bent).
The normal line
is the line that is perpendicular to the surface. It crosses the point where the incident ray hits the surface.
The angle of incidence is formed by
the ray and the normal.
The angle of refraction is formed by
the refracted ray and the normal.
What is myopia?
A person suffering from myopia, also known as near-sightedness can see objects that are close, but has difficulty seeing images that are farther away. This is due to an elongated eyeball, or lenses that are too thick. Their lenses bend the light too much, therefore the image is focused before the retina rather than directly onto it. This problem can be corrected with a divergent lens or biconcave lens, which will spread out or diverge the light rays so that they focus directly on the retina.
What is hyperopia?
A person suffering from hyperopia, also known as far-sightedness, can see distant objects clearly but nearby objects appear blurry. This defect is caused by a shorter eyeball or by a lens that is not curved enough. The lens is unable to converge the light onto the retina and the image is focused behind the retina. This problem can be corrected by a convergent or biconvex lens, which will bend the light more, bring the light rays closer together, focusing the image on the rentina.
What are biconcave lenses
Also known as divergent lenses. This type of lens causes light rays moving through it to diverge or split apart. It order to find the focal point of a divergent lens, you have to extend the refracted rays until they meet: this is actually called a virtual focal point.
What are biconvex lenses
Also known as convergent lenses. This type of lens causes light rays that move through it to converge to go closer together. The rays will always converge to a precise point, we call this the focal point of a lens.
Light rays under normal conditions
In a normal eye, not subjected to either myopia nor hyperopia, light enters the eye and is refracted so that the image is projected directly onto the retina which then transmits the light (stimulus) into a nerve impulse carried by the optic nerve and processed by the brain.
In other words:
Stimulus (light wave) - Recipient (eye) - Transformer (Retina) - Conductor (optic nerve) - Analyser (brain))
