eye

Question 1

iris

Answer 1

Circular sheet of muscles
Has pigment to give iotseye color
Controls amount of light entering the eye (circular muscles and radial muscles)

Question 2

conjunctiva

Answer 2

Thin transparent mucous membrane covering sclera
Mucous membrane that keeps the front of eyeball moist

Question 3

sclera

Answer 3

Tough, white, outer covering of eyeball
Continuous with cornea
Protects the eye from mechanical damage

Question 4

pupil

Answer 4

allows light to enter the eye

Question 5

eyelashes

Answer 5

Shields eyes from dust particles

Question 6

tear gland

Answer 6

Secretes tears
Washes the duct particles away
Keeps the cornea moist for atm oxygen to dissolve into. The dissolved oxygen diffuses into cornea
Lubricate conjunctiva, reducing friction when eyelids move

Question 7

eyelids

Answer 7

Protect cornea from mechanical damage
Squinting prevents excessive kight from entering the eye and damaging light sensitive tissues (retina) inside
Blinking spreads tears over the cornea and conjunctiva and wipes off the dust particles off cornea

Question 8

suspensory ligaments

Answer 8

Connective tissues that attaches edge of lens to ciliary body

Question 9

cornea

Answer 9

dome shaped transparent layer
Continuous with sclera
Refrcats and bends light rays into eye

Question 10

aqueous chamber

Answer 10

Filled with aqueous humour
Keeps eyeball firm
Refracts light into pupil

Question 11

lens

Answer 11

Transparent, circular, biconcave
Elastic
Changes shape/thickness to focus light into retina

Question 12

choroid

Answer 12

Pigented black to prevent interna reflectin of light
Contains blood vessels that bring oxygen and nutrients to eyeball and remove metabolic waste products

Question 13

vitreous chamber

Answer 13

Filled with vitreous humour
Keeps eyeball firm
Helps refract light rays into retina

Question 14

fovea

Answer 14

Directly behind lens
Contains greatest numbe of cones but has no rods (fc)
Allows for coloured detailed vision in bright light

Question 15

blind spot

Answer 15

Region where optic nerve leaves the eye
No rod and cones
No photoreceptors
Not sensitive to light
No image perceived by brain

Question 16

optic nerve

Answer 16

transmits nerve impulses to brain when phptoreceptrs in retina are stimulated

Question 17

retina

Answer 17

Light sensitive layer where images are formed
Contains photorecpetors
Contains rods and cones
Photorecpetors are connected to nerve endings from optic nerve

Question 18

bright light

Answer 18

Circular muscles contract
Radial muscles relax
Pupil constricts
Reduces amount of light enerting the eye

Question 19

dim light

Answer 19

Circular muscles relax
Radial muscles contract
Pupil dilates
Increases amount of light entering the eye

Question 20

relfex arc in dim light

Answer 20

Lowering of light intensity
Photorecpetors in retina are stimulated
Nerve impulses are generated and sent through sensory neurone in opticenerve to brain
In brain, nerve impulses are transmitted through a synapse to relay neurone then through another synapse to the motor neurone
The motor neurone trnamsits nerve impulses from brain to muscle in iris
Circular muscles of iris relaxes and radial muscles pf iris contracts
Pupil dilates, allowing more light to enter th light

Question 21

focusing on distant object

Answer 21

Ciliary muscles relax, pulling on suspnesory ligaments
Suspensory ligament become taut, pulling on the edges of lens
Lens become thinner and less convex
Increase focal length of lens
Light rays from the distant object are sharply focused onto the retina
Photorecpetors in retina are stimulated
Nerve impulses are transmitted by the optic nerve to brain
Brain interprets the impulses and person sees the object

Question 22

focusing on near object

Answer 22

Ciliary muscles contract, relaxing their pull on suspensory ligaments
Suspensory ligaments slacken, relaing their pull on the lens
Lons become thicker and more convex
Decreases in focal length
Lights rays from object is sharply focused onto the retina
Photorecpetos in retina is stimulated
Nerve impulsesare generated and transmitted by optic nerve to the brain
Brain interprets the image and person sees the object

Question 23

nuclear cataract on eye

Answer 23

disrupt ability of lens to refrcat light rays onto retina, difficulty for vision under dim light
lens cant adjust to focus on obj at diff dist
cloudy vision