Special Senses Part Two (smell, taste, vision, hearing)

Question 1

What is the “hole” in the middle of the iris?

Answer 1

pupil

Question 2

What “covers” the iris and the pupil?

Answer 2

cornea

clear and transparent

Question 3

The lens is a derivative of…

Where is the lens?

Answer 3

optic placode

posterior to iris

Question 4

What is the area responsible for the sharpest vision?

Answer 4

fovea

Question 5

The optic nerve is connected to neurons that go into where?

Answer 5

retina

coats inner surface of the eye

Question 6

What’s the name of the place where nerves come off of the retina and turn into the optic nerve?
What does this area NOT contain?

Answer 6

Optic disc “blind spot”

There are NO photoreceptors

Question 7

2 types of muscle in iris:

Answer 7

pupillary dilator
pupillary constrictor (sphincter)

Question 8

Pupil diameter…
Parasympathetic:
Sympathetic:

Answer 8

Parasympathetic: constricted
Sympathetic: dilated

Question 9

When the lens is FLAT, it means…

When the lens is THICK, it means…

Answer 9

Flat: object is far away; ciliary muscles are relaxed
Thick: object is close; ciliary muscles are contacted

Question 10

Accommodation reflex is what?

Answer 10

The autonomic adjustment of the eye to give us clear vision

Question 11

Nerves and activity associated with…
Distant vision:
Close vision:

Answer 11

Distant: no parasympathetic activity
Close: parasympathetic activity (CN 3)

Question 12

Functions, activity, and cranial nerves of these muscles…
Sphincter pupillae:
Dilator pupillae:
Ciliary body/muscle:

Answer 12

• Sphincter pupillae: constrict pupil (high light or calm) PARASYMPATHETIC (CN 3)
• Dilator pupillae: dilate pupil (low light, excitement, sex, fear) SYMPATHETIC (CN 3)
• Ciliary body/muscle: change shape of lens; PARASYMPATHETIC (CN 3)

Question 13

The eye, an extension of the brain, “folded in on itself” and created a double layer. What is the layer that the light hits first after it hits the retina? What is the second layer?

Answer 13

First layer: nerves that consolidate and regulate the information that’s coming from the photoreceptors
Second layer: photoreceptors

Question 14

What are photoreceptor cells?

Answer 14

rods and cones

*sensory!

Question 15

Rods:
Cones:

Answer 15

Rods: blacks, grays, motion
Cones: 3 types; colors

Question 16

What does it mean when someone is colorblind?

Answer 16

They have a defect in a certain kind of cone

Question 17

Muscles AND nerves associated with…
Blinking:
Winking:

Answer 17

Blinking: levator palpebrae superioris (CN 3) - unconscious
Winking: orbicularis occuli (CN 7) - conscious

Question 18

Tympanic membrane separates what?

Answer 18

external ear from the middle ear

Question 19

What does the middle ear house?

Answer 19

malleus, incus, stapes

Question 20

Sometimes the vibrations going into the ear are too strong. What is the “first” muscle that helps prevent damage by constricting? What is it innervated by?
What is it attached to?

Answer 20

Tensor tympani (CN V3)
Malleus

Question 21

Remember:
What is the stapes derived from?
What is the nerve for it?

Answer 21

Hyoid arch

facial nerve

Question 22

What is the muscle that attaches to the stapes to prevent damage from strong vibrations?
What is it innervated by?

Answer 22

Stapedius muscle

CN 7

Question 23

What 2 muscles tense up to reduce the amount of vibrations going into the ear?

Answer 23

Tensor tympani

Stapedius muscle

Question 24

The vibrations go to the malleus, then the incus, then to the stapes. Where do they go after that?

Answer 24

The stapes footplate sits inside the oval window; it transfers the vibrations to oval window by moving towards, away, towards, away

Question 25

The vibrations meet the basilar membrane and it moves up and down, which causes the hair cells to move up and down and they end up bending once they hit what?

Answer 25

Tectorial membrane

it DOES NOT move!

Question 26

What kind of gated channel is involved in hearing?

Answer 26

Mechanically gated channel

Question 27

Describe the pathway of hearing.

Answer 27

Vibration arrives at tympanum
It vibrates the malleus, then the incus, then the stapes
The stapes vibrates the oval window, causing pressure waves in the cochlea
Pressure waves distort the basilar membrane
Basilar membrane pushed hair cells against tectorial membrane
CN 8 carries signals to the brain

Question 28

What is the function of the round window?

Answer 28

It acts as a pressure relief

Question 29

The semicircular canal houses what? And then it houses what?

Answer 29

It houses semicircular ducts which is filled with the fluid that causes us be aware of positional changes

Question 30

At the base of the semicircular canal, what is responsible for rotational movement?

Answer 30

Ampulla

Question 31

What is responsible for linear movements, acceleration, and equilibrium?

Answer 31

Macula

Question 32

Inside an ampulla, there is a gelatinous mass called the _______ which has a base with ________ cells.

Answer 32

cupula

hair

Question 33

What pushes on the cupula and will move the hair cells?

Answer 33

The fluid around it

Question 34

Position of the cupula…
Upright:
Bends to left:
Bends to right:

Answer 34

Upright: at rest
Bends to left: move head to right
Bends to right: move head to left

Question 35

The macula also has a mass of gelatinous material, but unlike the cupula’s gelatinous mass, it is NOT influenced by what?

Answer 35

the fluid movement

Question 36

What is embedded inside the gelatinous mass of the macula?

Answer 36

minerals called statoconia (or otoliths)

Question 37

The statoconia is connected to the underlying structures by…

Answer 37

gelatin

*so there is a little delay

Question 38

The gravity causes the statoconia to do what? Then what happens?

Answer 38

slide slightly
act on the hair cells
*if it’s a strong enough stimulus, it will create an action potential