The Eye Flashcards
Function of the cornea
To focus light
What is the cornea?
A curved transparent disc at the front of the eye
Function of the pupil
Hole to allow light through to the retina. Controls how much light enters the eye.
What is the pupi
A circular opening whose size is controlled by the iris
What is the iris
A ring of muscles around the pupil
Function of the iris
To control the size of the pupil and the amount of light that can enter the eye.
What is the lens
A soft flexible transparent part of the eye behind the pupil
Function of the lens
Changes shape to fine tune where light is focused on the retina
What are the ciliary muscles
A ring of muscle which circles the lens
What is the function if the ciliary muscles
To control the size/ shape of the lens. When the ciliary muscles contact the lens gets fatter, when they relax, the lens gets thinner.
What are the suspensory ligaments
Strong fibres which attach the lens to the ciliary muscles
Function of the ciliary muscles
To control the shape of the lens to focus light ton the retina
What is the retina
The back part of the eye containing rod and cone cells.
Rod cells: sensitive to light intensity. Allows to see in very dim light
Cone cells: detect colour
Function of the retina
To detect light and colour
What is the optic nerve
A nerve leaving the eye and consists of neurones to carry impulses to the brain
Function of the optic nerve
To carry impulses to the brain
What is the fovea
The region bof the retina with the greatest number of cones.
What is the conjunctiva
A mucous membrane that covers the eye
Function of the conjunctiva
To prevent infection
What happens to the eye when focusing on a near object?
When near, ciliary muscles contract, suspensory ligaments loosen, lens becomes thicker and more convex so light rays are refracted more strongly
What happens to the eye when focussing on a far object?
Ciliary muscles relax, suspensory ligaments tighten, lens becomes thin and less convex so light rays are refracted less strongly.
What happens to the eye when exposed to bright light
Circular muscles contract, radial muscles relax making the iris wider and the pupil smaller.
What happens to the eye in dim light
Radial muscles contract, circular muscles relax making the iris narrower and the pupil dilated.
describe the structure of the cornea
Cornea: a curved transparent disc at the front of the eye. Focuses light.
describe the structure of the pupil
Pupil: a circular opening whose size is controlled by the iris (the coloured part of the eye)
describe the structure of the iris
iris: a ring of muscles with a hole in the middle (pupil). The iris controls how much light can enter the eye.
describe the structure of the lens
Lens: this is soft, flexible and transparent. It’s shape can be changed to fine tune the focussing of light onto the retina.
describe the structure of the cellar muscles
Ciliary muscles: a ring of muscle at the edge of the eye which circles the lens. When it contracts the lens gets fatter. When it relaxes, the lens gets thinner.
describe the structure of the suspensory ligaments
Suspensory Ligaments: strong fibres which attach the lens to the ciliary muscles.
describe the structure of the retina
Retina: contains light sensitive cells named rods and cones.
describe the structure of the optic nerve
Optic nerve: consists of many neurones which carry impulses from the retina to the brain.
describe the structure of the fovea
Fovea: the region of the retina with the greatest number of cone cells.
describe the structure of the conjunctiva
Conjunctiva: a mucous membrane that covers the eye to prevent infection.
describe the structure of the sclera
Sclera: outer white part if the eye.
