7. special senses

Question 1

special senses

Answer 1

eyes and ears

Question 2

eyes

Answer 2

-3 layered sphere filled with fluid
-special features (6)
fibrous tunic
vascular tunic
nervous (sensory) tunic
lens
anterior segment
posterior segment

Question 3

fibrous tunic parts

Answer 3

1. sclera (white)
avascular CT
2. cornea (transparent)
avascular CT
3.conjunctiva
-covers anterior sclera
-vascular mucous membrane
-when vessels dilate = bloodshot eyes

Question 4

vascular tunic parts

Answer 4

1. choroid (posterior)
   - contains melanin
   - highly vascular
2. ciliary body (anterior)
   - ciliary muscle + ciliary processes- focus the lens
3. iris
   - coloured part of eye
4. pupil
   - hole in iris

Question 5

nervous (sensory) tunic

Answer 5

=retina

Question 6

nervous tunic parts

Answer 6

outer pigmented layer
inner neural layer
fovea centralis
optic disc

Question 7

inner neural layer ( 3 layers )

Answer 7

1. photoreceptors (2 types)
rods- black and white
cones - colour
2. bipolar cells
3. ganglion cells 
-axons from optic nerve (cranial nerve 2)

Question 8

fovea centralis

Answer 8

-where light is focused
=area of greatest visual acuity
-no rods, just cones

Question 9

optic disc

Answer 9

blind spot where blood vessels and optic nerve exit eye

no rods or cones

Question 10

lens

Answer 10

• avascular, transparent

- cataracts = clouding of lens

Question 11

anterior segment

Answer 11

anterior to lens
-contains aqueous humour
(fluid similar to plasma)

Question 12

posterior segment

Answer 12

• posterior to lens
• contains vitreous humour
• gel-like

Question 13

ear features

Answer 13

external ear
middle ear
inner ear (labyrinth) 
cochlea
receptors in inner ear

Question 14

external ear

Answer 14

-conducts sound
parts:
auricle (pinna)
-elastic cartilage, covered with skin
external auditory (acoustic) canal (meatus)
tympanic membrane (eardrum)

Question 15

middle ear

Answer 15

conducts sound
parts:
eustachian tube
ear ossicles

Question 16

eustachian tube

Answer 16

also called pharyngotympanic tube

Question 17

ear ossicles

Answer 17

malleus
-secured to tympanic membrane
incus
stapes
-transmits sound to inner ear via oval window

Question 18

inner ear (labyrinth)

Answer 18

detects sound, involved with equilibrium
parts: bony labyrinth
and membranous labyrinth

Question 19

bony labyrinth

Answer 19

tunnels in temporal bone
contains perilymph
parts:
semicircular canals (equilibrium)
vestibule (equilibrium)
cochlea (hearing)

Question 20

membranous labyrinth

Answer 20

surrounded and protected bony labyrinth 
-contains endolymph
parts: 
semicircular ducts (inside canals)
utricle and saccule (inside vestibule)
cochlear duct (inside cochlea)

Question 21

cochlea

Answer 21

coiled

membraines

Question 22

cochlea coils

Answer 22

each coil has three channels
-scala vestibuli
upper, perilymph
-scala tympani
lower, perilymph
-cochlear duct
middle, endolymph

Question 23

cochlea membranes

Answer 23

vestibular membrane
basilar membrane
tectorial membrane

Question 24

vestibular membrane

Answer 24

b/w cochlear duct and scala vestibuli

Question 25

basilar membrane

Answer 25

b/w cochlear duct and scale tympani

Question 26

tectorial membrane

Answer 26

covers hair cells = receptor cells

Question 27

receptors in inner ear

Answer 27

hair cell that synapses with an associated neuron

• send impulses to brain by cranial nerve Vlll
• hairs=cilia that extend into endolymph
• tips of cilia embedded in tectorial membrane (stability)