6.1 Flashcards
(27 cards)
What does the cornea do
They focus light. It is supported my fluid. The cornea refracts light so it converges towards the retina. It does most of the focussing for our eye.
What is the cornea? What is it made up of?
It is made up of cells that are transparent enough to let light through. Yet they hold the eye together.
Where is your cornea?
At the very front of your eye
The are the two types of cells in your retina?
Rod and cone cells
If you are nearsighted your can not see thing?
Far away
If you are farsighted you can not see things?
Close up
How can nearsighted be corrected?
By using a concave lens. Because when you are nearsighted your light rays converge too early and the concave lens diverges them so they converge right at the retina.
How can you fix farsighted?
By using a convex lens. Because when your farsighted the light rays don’t converge early enough so the convex lens helps them do so.
What Is the pupil? And where is it on the eye?
The place where light enters. The pupil is an opening that appears dark because light passes through it without reflecting back. The pupil is the black circle that you can see on your eye.
What is the iris and wherein it on your eye?
It is the coloured circle, surrounding your pupil. It is muscle. The iris can control how much light gets into the eye by dilating or expanding to let more light in when in dim light situations and contracts to light less light in when in bright situations.
What surrounds the cornea?
The opaque tissue called sclera
What is sclera and where is it on the eye?
It is the white opaque tissue surrounding the iris and pupil.
What is behind the pupil?
A flexible on convex lens
What happens when light rays hit the retina?
The are focused onto its screen at the back of the eye where an image is formed.
How do we detect the image formed by the retina
With special light-sensitive cells and others convert the light rays into electrical signals that are sent to the brain.
How do the light images formed in the retina get to the brain?
By the optic nerve
What is the focal point in the eye?
The point where all the light rays converge together at the back of the eye to form an image on the retina
When does the lens focus?
After the light rays have gone through the pupil and cornea
How does the lens focus light rays
It focuses by using muscles to change it shape. When the muscles contract there is less tension allowing the lens to become thicker. A thicker lens can focus on near objects. To look at distant objects the same muscles relax allowing the lens to become thinner but the tension is higher.
The image the retina forms is inverted
Yes
How does the blind spot happen?
The spot where the optic nerve enters the retina does not have light sensing cells so no image for that spot can be formed
What type of coloured light do rod cells aborsbe?
Almost any colour and are very good at absorbing green light
What colours do cone cells absorb
They detect colour not absorb it
What are rod cell used for night or day vision?
Night
