Special Sense Organs

Question 1

eyeball primary components

Answer 1

1) fibrous tunic
2) vascular tunic
3) nervous tunic
4) lens
5) anterior chamber
6) posterior segment

Question 2

fibrous tunic

Answer 2

• consists of sclera + cornea (avascular CT)

Question 3

what covers the anterior surface of sclera?

Answer 3

CONJUNCTIVA

• vascular mucous membrane
• dilation of blood vessels result in blood shot eyes

Question 4

vascular tunic

Answer 4

• iris
• choroid is highly vascular
• contains ciliary body

Question 5

function of melanin in choroid

Answer 5

prevents reflection + scattering of light

Question 6

what is the ciliary body in the vascular tunic

Answer 6

contains ciliary muscle + processes control shape of lens and secrete aqueous humor

Question 7

nervous tunic

Answer 7

• retina: sensory portion
• fovea centralis + optic disc
• OUTER pigmented layer + INNER neural layer (3 layers of neurons)

Question 8

nervous tunic: layers of neurons

Answer 8

i. photoreceptor neurons: rods + cones
ii. bipolar cells
iii. ganglion cells: axons form cranial nerves [II optic nerve]

Question 9

nervous tunic: fovea centralis

Answer 9

• where light focuses

- greatest visual

Question 10

nervous tunic: optic disc

Answer 10

• blind spot

- optic nerve + blood vessels exit

Question 11

lens

Answer 11

transparent, avascular layer

Question 12

what happens when lens becomes cloudy?

Answer 12

CATARACTS

- can be caused by other things

Question 13

anterior chamber

Answer 13

• anterior to lens

- contains aqueous humor

Question 14

what is the aqueous humor?

Answer 14

• similar to blood plasma

- replaced every 90 mins

Question 15

where does aqueous humor go?

Answer 15

drains into sinus b/w sclera + cornea

Question 16

posterior segment

Answer 16

• posterior to lens

- contains gel-like vitreous humor (not replaced)

Question 17

ear consists of…

Answer 17

1) external ear
2) middle ear
3) inner ear

Question 18

external ear

Answer 18

• auditory canal (meatus)
• tympanic membrane (eardrum)
• auricle: elastic cartilage

function: conduct sound

Question 19

middle ear

Answer 19

• auditory ossicles
• eustachian tube (auditory tube)

function: conduct sound

Question 20

auditory ossicles contain

Answer 20

• malleus: against tympanic membrane
• incus
• stapes: against oval window of inner ear

Question 21

inner ear

Answer 21

CONTAINS:

• vestibular nerve
• boney + membranous labyrinth (surrounds + protects)

Question 22

INNER EAR: bony labyrinth

Answer 22

CONTAINS:

• semi circular canals
• cochlea
• vestibule
• lined w/ periosteum containing perilymph

Question 23

INNER EAR: membranous labyrinth

Answer 23

CONTAINS:

• semi circular ducts in canals (connect w/ utricle)
• cochlear duct in cochlea
• utricle + saccule in vestibule
• endolymph

Question 24

cochlea

Answer 24

• coiled structure (2.5 coils)

- 3 channels in each coil [scala vestibuli, tympani, media]

Question 25

COCHLEA: scala vestibuli location

Answer 25

above cochlear duct

Question 26

COCHLEA: scala tympani

Answer 26

below cochlear duct

- 1 & 2 contain perilymph (part of bony labyrinth)

Question 27

COCHLEA: scala media

Answer 27

cochlear duct

• continuation of membranous labyrinth (endolymph)
• has vestibular, basilar + tectorial membrane

Question 28

SCALA MEDIA: vestibular membrane

Answer 28

separates cochlear duct from scala vestibuli

Question 29

SCALA MEDIA: basilar membrane

Answer 29

separates cochlear duct from scala tympani

Question 30

SCALA MEDIA: tectorial membrane

Answer 30

covers hair cells of spiral organ

Question 31

what are the receptors of scala media?

Answer 31

hair like cells that synapse w/ neurons

- extend into endolymph

Question 32

functions of ear

Answer 32

1) CONDUCTION OF SOUND: middle + external
2) HEARING & EQUILIBRIUM: inner ear
3) DIRECT IMPULSES TO BRAIN: thru VIII - vestibulocochlear nerve