eye

Question 1

cornea
function and characteristic

Answer 1

transparent
refracts light rays into the eye

Question 2

sclera

function and characteristic

Answer 2

the outermost layer of the eye
tough, white covering; continuous with cornea

protects eyeball from mechanical damage

Question 3

aqueous humour

function and characteristic

Answer 3

space between lens and cornea
filled with aqueous humour
keep the front of the eyeball firm and helps to refract light into the pupil

Question 4

iris

function and characteristic

Answer 4

controls the size of the pupil; allows different intensities of light to enter the eye
comprised of circular muscles and radial muscles

Question 5

pupil

function and characteristic

Answer 5

hole in the center of the iris
allows light to enter the eye

Question 6

ciliary body

function and characteristic

Answer 6

contains ciliary muscles
controls the curvature/thickness of the lens

Question 7

suspensory ligament

function and characteristic

Answer 7

connective tissue that attaches the edge of the lens and the ciliary body

Question 8

lens

function and characteristic

Answer 8

transparent, circular and biconvex structure
elastic - able to change its shape or thickness by suspensory ligament and ciliary body
to refract light on the retina

Question 9

vitreous chamber
function and characteristic

Answer 9

filled with vitreous humour
keeps eyeball firm and refract light onto the retina

Question 10

retina

function and characteristic

Answer 10

innermost layer of the eye
light-sensitive layer; contains photoreceptors (rods and cones)

Question 11

fovea (yellow spot)

function and characteristic

Answer 11

region on the retina where image is focused
greatest concentration of cones; no rods

Question 12

choroid

function and characteristic

Answer 12

middle layer of the eye
pigmented black to prevent internal reflection of light
richly supplied with blood vessels to transport nutrients and waste to and from the eye

Question 13

optic nerve

function and characteristic

Answer 13

nerve that transmits nerve impulses to the brain when the photoreceptors in the retina are stimulated

Question 14

blind spot

function and characteristic

Answer 14

region where optic nerve leaves the eye
does not contain rods or cones
not sensitive to light

Question 15

why is having a pupil reflex important?

Answer 15

to prevent excessive light from entering the eye and damaging the retina

also allows more light to enter the eye under low light condition

Question 16

in bright light / when light intensity increases

Answer 16

photoreceptors on the retina detect the high intensity of light, generating nerve impulses.
nerve impulses are transmitted along the sensory neurone in the optic nerve, to the relay neurone in the brain, to the motor neurone, across the motor end plate to the iris(effector).
circular muscle contracts, radial muscle relaxes
pupil constricts / pupil diameter decreases.

Question 17

in dim light / when light intensity decreases

Answer 17

photoreceptors on the retina detect the low intensity of light, generating nerve impulses.
nerve impulses are transmitted along the sensory neurone in the optic nerve, to the relay neurone in the brain, to the motor neurone, across the motor end plate to the iris(effector).
circular muscle relaxes, radial muscle contracts
pupil dilation occurs / pupil diameter increases

Question 18

when an object is far,

Answer 18

light rays of far object fall before the retina
detected by photoreceptors in the retina, which generate nerve impulses
nerve impulses transmitted along the sensory neurone in the optic nerve to the relay neurone in the brain, to the motor neurone, across the motor end plate, to the ciliary muscle.
ciliary muscles relax, and the suspensory ligament become taut, and pull on the edges of the lens
the lens become thinner and less biconvex, increasing the focal length of the lens
allowing the image to be focused clearly onto the retina

Question 19

when an object is near,

Answer 19

light rays of near object fall behind the retina
detected by photoreceptors in the retina, which generate nerve impulses
nerve impulses transmitted along the sensory neurone in the optic nerve to the relay neurone in the brain, to the motor neurone, across the motor end plate, to the ciliary muscle.
ciliary muscles contract, and the suspensory ligament slackens, relaxing their pull on the edges of the lens
the lens become thicker and more biconvex, decreasing the focal length of the lens
allowing the image to be focused clearly onto the retina