Eyes (triple only) Flashcards
Name the process used to focus light from near and far objects
Accommodation
What stimuli are the receptors of the eye sensitive to?
Light intensity
Colour (wavelength of light)
Whihc part of the eye is responsible for changing the amount
of light entering the eye?
Iris
Identify the conditions present in diagram A and B
A = Bright light
B = Dim light
The lens can change shape to focus light from near and far objects.
What is the name of this process?
Accommodation
Describe the structure and function of the retina
Found at the back of the eye
Contain light sensitive cells (rods and cones)
Light sensitive cells send impulses to the brain
Name the part of the eye labelled 1
Cornea
Name the part of the eye labelled 2
Pupil
Name the part of the eye labelled 3
Iris
Name the part of the eye labelled 4
Lens
Name the part of the eye labelled 5
Retina
Name the part of the eye labelled 6
Ciliary muscle
Name the part of the eye labelled 7
Optic nerve
Describe the structure and function of the optic nerve
Optic nerve connects the eye and the brain
Contains sensory neurones
Send electrical impulses from the retina to the brain
Describe the structure and function of the sclera
Tough outer layer of the eye
Protects internal structures
Describe the structure and function of the cornea
Curved transparent layer at the front of the eye
Lets light into the eye
Allows light to be focussed on the retina
Describe the structure and function of the iris
Iris is a muscle
Controls the size of the pupil by contracting and relaxing the muscles
Allows the eye to adjust to bright and dim light
Describe the structure and function of the ciliary muscles and
suspensory ligaments
Hold the lens in place
Can change the shape of the lens
Describe how the iris alters the size of the pupil in bright ight
Circular muscles contract
Radial muscles relax
Makes pupil smaller so less light can enter the eye
Describe how the iris alters the size of the pupil in dim light
Circular muscles relax
Radial muscles contract
Makes pupil larger so more light can enter the eye
Describe how the eye changes the shape of the lens when focussing on near objects
Ciliary muscle contract
Suspensory ligaments loosen
Lens becomes thicker and more curved
Light is refracted strongly
Image forms on the retina
How does the eye focus on distant objects?
Ciliary muscles relax
Suspensory ligaments tighten
Lens is puller thinner
Light is refracted less strongly
Image falls on the retina
What condition does this person suffer from?
Short sighted
Myopia
What is myopia?
Short-sightedness
Lens becomes too curved
Light is focused in front of the retina
Images appear blurry
How can myopia be treated?
Using glasses or contact lenses
Concave lens
Spreads the light so they can be focused on the retina
Name the condition this person suffers from
Long sightedness
Hyperopia
What is hyperopia?
Long-sightedness
Lens is too flat
Light is focused behind the retina
Images appear blurry
How can hyperopia be treated?
Using glasses or contact lenses
Convex lens
Brings light rays together
Image formed on the retina
What is laser eye surgery?
Use lasers to fix visual defects n adults
Myopia - laser reduces the thickened of the cornea so light is refracted less strongly
Hyperopia - laser alters curvature of the cornea so light is refracted correctly
How can replacement lenses by used to treat visual defects?
Replacement lens replaces the natural lens
What are the risks of lens replacement?
Can cause retinal damage, cataracts and infections
