the human eye

Question 1

what is the cornea & its functions?

Answer 1

• transparent lens
• refracts light as it enters the eye
• is also protective for the inner eye

Question 2

what is the pupil?

Answer 2

a hole that allows light to enter the eye

Question 3

what is the iris?

Answer 3

• the coloured part of the eye
• controls the pupil- therefore controls how much light enters the eye

Question 4

what is the lens?

Answer 4

• disc full of fluid
• transparent- focuses light onto the back of the eye
• can change shape depending on how close the object is

Question 5

what is the lens full of?

Answer 5

fluid

Question 5

what does the retina contain?

Answer 5

light receptor cells- rods & cones

Question 5

what can cones do?

Answer 5

detect colour

Question 5

what are rods sensitive to?

Answer 5

light intensity- can see how bright an object is

Question 6

what is the optic nerve?

Answer 6

a sensory neurone carrying impulses between the eye and the brain

Question 7

what is the lens controlled by?

Answer 7

• ciliary muscles which can contract and release to change the shape of the lens
• suspensory ligaments which connect the muscle to the lens

Question 8

what is the eye?

Answer 8

a highly specialised sense organ containing receptor cells that allow us to detect the stimulus of light

Question 9

what are the ciliary muscles?

Answer 9

a ring of muscle that contracts and relaxes to change the shape of the lens

Question 10

what are the suspensory ligaments?

Answer 10

ligaments that connect the ciliary muscle to the lens

Question 11

what is the sclera?

Answer 11

the strong outer wall of the eyeball that helps to keep the eye in shape and provides a place of attachment for the muscles that move the eye

Question 12

what is the fovea?

Answer 12

a region of the retina where the eye sees particularly good detail as it has the highest density of cones

Question 13

what is the aqueous humour?

Answer 13

the watery liquid between the cornea and the lens

Question 14

what is the vitreous humour?

Answer 14

the jelly-like liquid filling the eyeball

Question 15

what is the choroid?

Answer 15

a pigmented layer of tissue lining the inside of the sclera that prevents the reflection of light rays inside the eyeball

Question 16

what is accommodation?

Answer 16

how the lens brings about focusing of light to see

Question 16

where is the vitreous humour located?

Answer 16

at the back of the eye

Question 16

what is the blind spot?

Answer 16

the point at which the optic nerve leaves the eye- there are no receptor cells

Question 16

how can the lens’ shape change?

Answer 16

when the suspensory ligaments tighten or relax

Question 16

where is the aqueous humour located in the eye?

Answer 16

at the front of the eye

Question 17

where does accommodation happen?

Answer 17

at the back of the eye

Question 18

when an object is close?

Answer 18

• ciliary muscles contract
• suspensory ligaments loosen
• stops the suspensory ligaments from pulling on the lens- allows the lens to become fatter
• light is refracted more

Question 19

when an object is far away?

Answer 19

• ciliary muscles relax
• suspensory ligaments tighten
• suspensory ligaments pull on the lens
• light is refracted less

Question 20

what is the pupil reflex?

Answer 20

a reflex action carried out to protect the retina from damage

Question 21

pupil in dim light?

Answer 21

• pupil dilates to allow as much light in as possible
• radial muscles contract
• circular muscles relax

Question 22

pupil in bright light?

Answer 22

• pupil constricts to prevent too much light coming in and damaging the retina
• radial muscles relax
• circular muscles contract