chap10: the eye

Question 1

function of sclera

Answer 1

provides eyeball from mechanical damage

Question 2

function of conjunctiva

Answer 2

mucus membrane that secrete mucus which keeps the front of the eyeball moist

Question 3

function of the sclera

Answer 3

white part of the eyeball
protects the eye from mechanical damage

Question 4

function of conjunctiva

Answer 4

secretes mucus to keep the eyeball moist

Question 5

function of eyelashes

Answer 5

shields eye from dust particles

Question 6

function of the tear duct

Answer 6

secretes tears that wash away dust particles
keep the cornea moist for atmospheric oxygen to dissolve so that dissolved oxygen can diffuse into the cornea
lubricate the conjunctiva to reduce friction when eyelids move

Question 7

function of eyelids

Answer 7

eyelids protect cornea from mechanical damage
can be partly closed (squinting) to prevent too much light from entering the eye and damaging the retina
blinking spreads tears over the cornea and conjunctiva and wipes dust particles off the cornea

Question 8

function of the iris

Answer 8

controls the size of the pupil and the amount of light that enters

Question 9

function of pupil

Answer 9

a hole in the centre of the iris that allows light to enter the eye

Question 10

function of the ciliary body

Answer 10

contains ciliary muscles that controls the curvature/thickness of the lense

Question 11

function of the suspensory ligament

Answer 11

connective tissues that attaches the edge of the lens to the ciliary body

Question 12

function of the cornea

Answer 12

refracts/bends light rays into the eye
causes the greatest refraction into the eye

Question 13

function of the aqueous chamber

Answer 13

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

Question 14

function of the lens

Answer 14

transparent, circular and biconvex
elastic and changes its shape/thickness to focus light onto the retina

Question 15

function of the retina

Answer 15

contains photoreceptors that are connected to the nerve endings from the optic nerve

Question 16

function of the blind spot

Answer 16

the region of the eye where the optic nerve leaves the eye and does not contain any photoreceptors, therefore is not sensitive to light and prevents an image to be seen

Question 17

function of the optic nerve

Answer 17

it is the nerve that transmits nerve impulses to the brain where the photoreceptors in the retina are stimulated

Question 18

function of the fovea

Answer 18

it is a small depression in the retina, behind the lens. this is where images are normally focused. it contains the greatest amount of photoreceptors which enables a person to have detailed coloured vision in bright light

Question 19

function of the choroid

Answer 19

pigmented black to prevent internal light refraction
contains blood vessels that bring oxygen and nutrients to the eyeball and remove metabolic waste products

Question 20

function of the choroid

Answer 20

pigmented black to prevent internal light refraction
contains blood vessels that bring oxygen and nutrients to the eyeball and remove metabolic waste products

Question 21

function of vitreous chamber

Answer 21

contains vitreous humour that keeps the eyeball firm and helps light refract onto the retina

Question 22

what is a pupil reflex

Answer 22

automatic, immediate response
prevents excessive light from entering the eye and damaging the retina

Question 23

action of the iris in bright light

Answer 23

circular muscles of the iris contract
radial muscles of the iris relax
pupil constricts and reduces the amount of light entering the eye

Question 24

action of the iris in dim light

Answer 24

radial muscles of the iris contracts
circular muscles of the iris relaxes
pupil dilates to increase the amount of light entering the eye

Question 25

pathway of nerve impulses in the pupil reflex

Answer 25

stimulus -> receptors in retina -> sensory neurons in the optic nerve -> brain -> motor neurone -> effector in iris muscles

Question 26

what is focusing

Answer 26

focusing is accommodation and adjustment of lens of the eye so that clear images of objects at different distances are formed on the retina

Question 27

what happens when the eye focuses on a distant object

Answer 27

ciliary muscles relax
suspensory ligaments become taut
lens becomes thinner and less convex
light rays from distant objects are sharply focused on the retina
photoreceptors are stimulated
nerve impulses produced are transmitted by the optic nerve to the brain
the brain interprets the nerve impulses, and the person sees the distant object

Question 28

what happens when the eye is focusing on a near object

Answer 28

ciliary muscles contract
suspensory ligaments slacken
the lens becomes thicker and more convex
light rays from near object are sharply focused on the retina
photoreceptors are stimulated
nerve impulses produced are transmitted by the optic nerve to the brain
the brain interprets the nerve impulses and the person sees the near object