cells + control // the eye Flashcards
Identify the main parts of the eye
(Identify the main parts of the eye, I can’t upload pics on here :/)
Explain how the cornea is adapted to its functions
the cornea contains no blood vessels to nourish or protect it against infection so it can be transparent and refract light.
How is the iris adapted to its function
the iris is adapted to be able to change the size of the pupil’s opening. it does this so that it can regulate the amount of light that enters the eye.
How’s the retina adapted to its function
it’s transparent so that light rays can enter the eye.
How is the lens adapted to its function
it can change its shape so that it can focus the light rays that pass through it (and onto the retina) thus, being able to create clear images of objects that are positioned at various distance
Explain how receptor cells allow full colour vision in bright light
They respond to light entering your eye, which is why they are called photoreceptors. When light strikes these pigments, they briefly lose their colour. This bleaching process triggers nerve impulses, which are transmitted to your brain via your optic nerve.
Describe cataracts
Cataracts are when the lens develops cloudy patches. Over time these patches usually become bigger causing blurry, misty vision and eventually blindness.
Describe short-sightedness
Short-sightedness, or myopia, is a very common eye condition that causes distant objects to appear blurred, while close objects can be seen clearly.
Short sight is caused by one of the following: The eyeball being elongated - so that the distance between the lens and the retina is too great.
Describe long-sightedness
Long-sightedness affects the ability to see nearby objects. You may be able to see distant objects clearly, but closer objects are usually out of focus. The medical name for long-sightedness is hyperopia.
Long-sightedness is caused by one of the following: the eyeball being too short - so the distance between the lens and retina is too small.
Describe colour-blindness
When someone finds it difficult to identify and distinguish between certain colours.
The retina at the back of the eye contains receptor cells called cones that are sensitive to red, green or blue light. People with colour blindness have a lack of receptors, or defects in them. People with red-green colour blindness, for example, have difficulty distinguishing shades of red and green.
Describe how cataracts are treated
removing the lens and replacing with a plastic lens
Explain how long-sightedness can be corrected
Long-sightedness is corrected by putting a convex lens in front of the eye. Convex lenses converge light rays from a nearby object before they enter the eye, moving the focus back onto the retina
Explain how short-sightedness can be corrected
Short-sightedness can be corrected by placing a concave lens in front of the eye, as shown in the diagrams below. Concave lenses bend light outward making objects from afar look larger.
