SPECIAL SENSES

Question 1

What is the Iris?

Answer 1

Coloured ring
Supplied by PNS/SNS

Question 2

What is the lens (eye)

Answer 2

Consists of fibres that can alter thickness
- used to focus objects

Question 3

What is the cornea

Answer 3

Clear membrane which is convex and allows refracting light to travel through and reach retina

Question 4

What is the sclera (eye)

Answer 4

White of the eye

Question 5

What is the conjunctiva?

Answer 5

Membrane that lines eyeball and eyelid
Moistens/lubricates surface area of the eye

Question 6

What is the retina?

Answer 6

-inner lining of the eye
- contains sensory receptor cells (pons/cones)
-converts light to nerve impulses and images are projected
- colour perception

Question 7

Physiology of sight

Answer 7

1) light comes into eye
2) light passes through cornea and pupil
3) iris regulates amount of light entering
4) light is refracted by lens
5) light enters retina
6) light rays stimulate pons and Cones
7) impulses conveyed by optic nerve to brain
8) cerebral cortex interprets sensory impulses as vision

Question 8

What are rods and cones?

Answer 8

Photoreceptors
Light detecting cells on the retinas at the back of the eye

Question 9

How long is the auditory canal?

Answer 9

2.5cm

Question 10

What is the purpose of ceremonious glands?

Answer 10

Excrete ear wax

Question 11

What are the auditory ossicles?

Answer 11

3 tiny bones that form a chain behind the tympanic membrane
Bones vibrate when exposed to sound

-malleus
-incus
-stapes

Question 12

What are the parts of the inner ear?

Answer 12

Vestibule
Semicircular canal
Cochlea

Question 13

What is the vestibule?

Answer 13

Part of the inner ear that contains the utricle and saccule (membranes)
- important in balance

Question 14

What are the semicircular canals (ear)

Answer 14

Continuation of vestibule
-important for balance

Question 15

What is the cochlea?

Answer 15

• snail shell
• sensory receptor for sound
• links with vestibular nerve (8th cranial)

Question 16

Physiology of hearing

Answer 16

1) pinna collects sound and concentrates into ear canal
2) tympanic membrane vibrates

3)vibrations transmitted and amplified through middle ear by movement of ossicles
4) pressure enters cochlear which stimulates auditory receptors creating auditory nerve impulses

5) nerve impulses travel up vestibulacochlear nerve to auditory nuclei in medulla -> then conducted to auditory centre in cerebrum

Question 17

Physiology of balance

Answer 17

1) semicircular canal and vestibule = balance and equilibrium
2) 3 semicircular canals position in space
3) change of position causes movement of endolymph (fluid)
4) this stimulates receptor in utricle/saccule/ampoule
5) nerve impulses transmitted by vestibular nerve which joins cochlear nerve (vestibularcocklear) up to cerebrum