Eyes

Question 1

Sclera

Answer 1

• tough outer covering (white of the eye)
• maintains shape and protect

Question 2

Cornea

Answer 2

• bulge of the sclera at front of eye (transparent)
• allows light entry into eye (bends light)
• needs oxygen but no blood vessels. get oxygen from tears

Question 3

Retina

Answer 3

• made up of rod (light level) & cone ( red, blue green) cells
• convert light wave to nerve impulse

Question 4

Aqueaus humour

Answer 4

• transparent fluid in chamber behind cornea
• supplies nutrients to cornea
• maintans shape
• no blood bc cornea needs to be clear

Question 5

Choroid layer

Answer 5

• middle layer
• has blood vessels to nourish retina
• has melanin
• absorb blue light

Question 6

3 layers from outer to inner

Answer 6

1. Sclera
2. Choroid
3. Retina

Question 7

Iris

Answer 7

• thin circular muscle
• coloured part of eye
• controls size of pupil (constriction/dilation)

Question 8

lens

Answer 8

• opening that allow light in eye
• focus the image on the retina
• bends light but also FOCUS

Question 9

ciliary muscle

Answer 9

• alter shape of lens

Question 10

vitreous humour

Answer 10

• cloudy jelly like material
• fills the eye interior chamber
• maintain shape of eye
• permit light transmission to retina

Question 11

fovea centralis

Answer 11

• area at centre of retina where cones are most dense and vision is sharpest
• rods are around it but not in it
• colour/light reception

Question 12

blind spot

Answer 12

no rods or cones here
- optic nerve comes in contact with retina
- absence of photosensitive cells therefore called blind spot

Question 13

rod

Answer 13

photoreceptor that operate in dim light to detect light in black and white
- used for peripheral vision (at the periphery of the retina)
- see black and white only
- low energy to activate so use @ night and peripheral vision
- one type therefore monochromatic vision
- many rods connected to one bipolar cell therefore retinal convergence

Question 14

cones

Answer 14

photoreceptors that operate in bright light (high intensity light) to identify colour
- 3 types (red, green, blue)
- cone shaped
- at the fovea so oy have enough energy to do an impulse
- high energy to activate
- one cone to one bipolar cell therefore no convergence

Question 15

_______ in charge of colour vision

Answer 15

cones

Question 16

lens ____ for focus on distant objects

Answer 16

flatten/elongated
muscles relax

Question 17

lens _____ for focusing on near objects

Answer 17

rounded
muscles contract

Question 18

Pathway to see

Answer 18

1. Light enters the eye through the pupil and reaches the retina
2. Absorbed by photocells (rods + cones)
3. Passed to bipolar cells
4. Passed to ganglion cells
5. Optic nerve

Question 19

Far sighted

Answer 19

• hyperopia
• can’t see things close up
• eyeball is too short causing image to focus behind retina
• solution: biconvex lens

Question 20

Near sighted

Answer 20

• myopia
• cant see things far away
• eyeball too long and lens cant flatten enough. image is in front of retina.
• solution: concave lens

Question 21

cataracts

Answer 21

clouding of lens

Question 22

glaucoma

Answer 22

pressure build up of aqueous humour

Question 23

astigmatism

Answer 23

lens or cornea irreglar shaped

Question 24

after images ( - & + )

Answer 24

after image: when you look at an optical illousion and see an image after

negative image: fatigue of the cones.

positive image: overstimulation of rods + cones (eg: seeing spots after staring at the sun)

Question 25

Chemical in rods?

Answer 25

rhodopsin

Question 26

Chemicals in cones?

Answer 26

Photopsin