eye and ear

Question 1

tough outer coat of eye, visible white coat

Answer 1

sclera

Question 2

transparent window which allows light to enter eye

Answer 2

cornea

Question 3

coloured ring of tissue

Answer 3

iris

Question 4

hole which lets light through

Answer 4

pupil

Question 5

dark layer underneath sclera which contains many pigment cells and blood vessels

Answer 5

choroid

Question 6

place where light energy is converted to nerve impulses at back of the eye

Answer 6

retina

Question 7

nerve which carries impulses to brain

Answer 7

optic nerve

Question 8

place where cones are concentrated

Answer 8

fovea

Question 9

how does pupil constrict when bright light enters

Answer 9

circular ms contract and radial ms relax

Question 10

what are the adv of having 2 eyes

Answer 10

cancelling blind spot
wider field of vision
stereoscopic vision
better sense of distances

Question 11

what are the changes that occur that allow distant objects to be seen

Answer 11

ciliary ms relax
suspensory ligaments are pulled tight
lens flat

Question 12

state cause, result and method of correction for long sight

Answer 12

cause: lens not convex enough or eyeball too short
result: light focused beyond retina
method of correction: convex lens to converge light before it enters the eye

Question 13

state cause, result and method of correction for short sight

Answer 13

cause: lens too convex or eye ball too long
result: light focused short of retina
method of correction: concave lens to converge lens before it enters the eye

Question 14

discuss the differences between regular and irregular astigmatism

Answer 14

regular: occurs when surface of cornea or lens is not perfectly spherical but rounder in one direction than the other
person’s eye will be in focus in one direction but not the other
corrected by glasses or lenses
irregular: curvature of cornea or lens is in more than one direction
corrected by lenses only

Question 15

what is a cataract and how is it treated

Answer 15

a condition in which the lens becomes cloudy and opaque so person is unable to see
can only be treated by surgery
lens is replaced by artifical lens

Question 16

outer ear function

Answer 16

directs sound waves to ear drum

Question 17

3 small bones that allow vibrations to pass and amplify vibrations

Answer 17

malleus, incus and stapes (ear ossicles)

Question 18

function of euctachian tube

Answer 18

connects middle ear with throat and this allows pressure to be equalized either side of the ear drum

Question 19

where are receptor cells that convert vibrations to nerve impulses found

Answer 19

organ of cort

Question 20

part of ear which senses balance

Answer 20

semi circular canals