The Eye and Ear

Question 1

Role of Eyelids

Answer 1

To cover and protect the eye

Question 2

Role of Conjunctiva

Answer 2

Transparent thin lining that protects the cornea

Question 3

Role of Cornea

Answer 3

Focus light on the retina

Question 4

Role of Sclera

Answer 4

Tough fibrous outer layer; the white of the eye: it maintains the eyes shape

Question 5

Role of Choroid

Answer 5

Contains blood vessels to supply food and oxygen to the cells of the eye

Question 6

Role of Retina

Answer 6

Innermost layer of the eye that contains receptor cells

Question 7

Role of Fovea

Answer 7

Where vision is best (mostly cones)

Question 8

Role of Iris

Answer 8

Contains blood vessels and melanin (gives colour of the eye), Controls amount of light that enters the eye through the pupil.
Contraction and expansion is a reflex

Question 9

Role of Pupil

Answer 9

In bright light the pupil constricts

In dim light the pupil dilates

Question 10

Role of Ciliary Body/Muscle

Answer 10

Thickened end of choroid that controls the shape of lens

Question 11

Role of Suspensory Ligaments

Answer 11

Hold the lens in place

Question 12

Role of Lens

Answer 12

Acts as a magnifying glass, it focuses light rays on the retina for very sharp images

Question 13

Role of Aqueous Humour

Answer 13

Watery liquid that supplies the lens and cornea with nutrients and helps keep the shape of the cornea and lens

Question 14

Role of Vitreous Humour

Answer 14

Gel that helps maintain the shape of the eye

Question 15

Define Blind Spot

Answer 15

Where the optic nerve passes through the retina and there is no room for receptors

Question 16

Role of Optic Nerve

Answer 16

When light rays focus on retina receptor cells are stimulated and impulses are carried along the optic nerve to the brain

Question 17

Outline the role of Rods in the eye

Answer 17

Receptor cells that see black and white
Only work in dim light
Better peripheral vision at night due to this

Question 18

Outline the role of Cones in the eye

Answer 18

Less numerous than rods
They are for colour vision
3 types in humans red, green and blue

Question 19

How do images form on the retina

Answer 19

Light reflects from object into the eye
The cornea and lens refract (bend) the light rays
Image is formed upside down on the retina

Question 20

Define Accommodation

Answer 20

The ability of the lens to change its shape to form a clear image

Question 21

Describe the eye during close vision

Answer 21

For close vision the ciliary muscle contracts, the suspensory ligaments relax and the lens becomes thicker

Question 22

Describe the eye during distant vision

Answer 22

When the eye is at rest, the lens is thin, has a long focal length and is adapted for seeing distant objects

Question 23

Name 2 eye defects and the method of treatment

Answer 23

Long sighted or hypermetropia and can be solved with Convex lens glasses
and
Short sighted or myopia and can be solved with concave lenses

Question 24

Role of Pinna

Answer 24

Funnels sound into the ear

Question 25

Role of Ear Canal

Answer 25

Has hairs and wax glands to trap dirt and germs

Question 26

Role of Eardrum

Answer 26

Vibrates when sound waves hit it

Question 27

What is the middle ear

Answer 27

Air filled cavity containing 3 small bones and Eustachian tube

Question 28

Role of Ossicles

Answer 28

3 small bones the hammer, anvil and stirrup; they amplify sound

Question 29

Role of Eustachian Tube

Answer 29

Keeps air pressure equal on each side of the eardrum, opens when we swallow and cough

Question 30

What is the Inner Ear

Answer 30

Contains coiled fluid filled tube called the cochlea and semi circular canals

Question 31

Role of Cochlea

Answer 31

Contains nerves that convert sound vibrations into electrical impulses

Question 32

Semi-Circular Canals

Answer 32

Help us keep balance and posture

Question 33

Explain how human being hear

Answer 33

The pinna channels sound vibrations towards eardrum which then vibrates This vibrates the hammer, anvil and stirrup which amplify sound The stirrup pushes on the oval window which pushes liquid inside the cochlea Special hairs on 30,000 receptor cells detect the movement and send signals along auditory nerve The brain interprets these as sound and we hear

Question 34

Explain how human beings balance

Answer 34

Head movements are detected by nerves in canals Vestibular nerve send messages to brain Brain responds by sending messages through the cerebellum which trigger reflexive actions in our muscles This helps keep the body balanced as we move

Question 35

Name 2 ear defects the causes and treatment

Answer 35

Otitis Media; caused by bacterial infection; treat with antibiotics and Glue Ear in children; build up of fluid in middle ear; install grommet to drain fluid, which then falls out

Question 36

Draw a diagram of the eye

Answer 36

Question 37

Draw a diagram of the ear

Answer 37