Special Senses

Question 1

Describe the sensory pathway from receptor to brain.

Answer 1

A stimulus generates a receptor potential -> triggers an action potential in the sensory nerve -> Action potential travels to the brain where it is ”sensed”

Question 2

How are receptor potentials different than action potentials?

Answer 2

The receptor potential triggers an action potential in the sensory nerve

Question 3

Where are the special senses located?

Answer 3

Special senses are localized and
confined to the head region

Question 4

What kind of papillae have taste buds?

Answer 4

Vallate (circumvallate) papillae, Fungiform papillae, Foliate papillae

Question 5

Detail the pathway from receptor to cortex for gustation.

Answer 5

Taste receptors-> sensory nerve fibers in cranial nerves -> brainstem -> thalamus -> gustatory cortex (insula)

Question 6

What contributes to the flavor of a substance?

Answer 6

Dissolved molecules in saliva enter taste pore -> Molecules bind to receptors on gustatory hair cells

Question 7

What kind of receptor is involved with olfaction?

Answer 7

Chemoreceptors

Question 8

What bone do the olfactory receptor cells pass through as they enter the brain?

Answer 8

Cribriform plate of ethmoid bone

Question 9

Detail the paths from receptor to brain for olfaction.

Answer 9

filaments of olfactory nerve-> Enter CNS through cribriform plate of ethmoid bone -> Synapse with mitral cells in olfactory bulb at glomeruli ->Limbic system -> Primary olfactory cortex in temporal lobe

Question 10

What are some disorders of smell?

Answer 10

Anosmia = absence of smell
Uncinate fits = olfactory hallucinations

Question 11

Follow the flow of tears from production to drainage into the nose

Answer 11

Tears move across eye -> enter puncta -> Drain into lacrimal canaliculi -> Lacrimal sac -> Nasolacrimal duct -> Nasal cavity

Question 12

What type of muscles help the eyeballs move?

Answer 12

Skeletal muscles

Question 13

What is strabismus? What is amblyopia?

Answer 13

Strabismus = misaligned eyes (cross-eyed)
Amblyopia (reduced vision in the weaker eye “lazy eye”)

Question 14

How does eye positioning influence 3D vision?

Answer 14

3D vision relies on both eyes working together to accurately focus on the same point in space. The brain is then able to interpret the image the each eye sees to create your perception of depth.

Question 15

List from the outermost to the innermost layers (tunics) of the eye.

Answer 15

Fibrous tunic , Vascular tunic, Sensory tunic

Question 16

What are the structures covered that make up the fibrous tunic?

Answer 16

Sclera, Cornea

Question 17

What is a difference between the sclera and the cornea?

Answer 17

Sclera is the white opaque area surrounding the iris of the eye
The cornea is the clear covering of the eye over the iris

Question 18

What are structures covered that make up the vascular tunic?

Answer 18

The structures of the eye that make up the vascular tunic is the Choroid and the Iris

Question 19

How are blue and brown eyes different?

Answer 19

Darker colored eyes have more pigment in anterior region of iris. Light eyes have little to no pigment in the anterior region.

Question 20

What makes up the ciliary body?

Answer 20

Ciliary muscle, Suspensory ligaments

Question 21

What happens to the ciliary muscle and suspensory ligaments when looking at close objects? Distant objects?

Answer 21

Close objects: Ciliary muscle contracts, Suspensory ligaments slacken
Distant objects: Ciliary muscle relaxes, Suspensory ligaments become taut

Question 22

What is the innermost tunic of the eye? What two layers make up this tunic?

Answer 22

Sensory tunic: Pigmented layer, Neural layer

Question 23

Describe how the cells that make up the neural layer are oriented to each other. How does light entering the eyes travel through these layers? Which cells respond to light?

Answer 23

• Photoreceptor cells : Rods (Most numerous in periphery of retina) and cones (Concentrated in central part of retina)
• Bipolar cells : Activated by rods and cones
• Ganglion cells : Activated by bipolar cells

Question 24

What cells form the optic nerve?

Answer 24

axons of ganglion cells

Question 25

Compare rods and cones

Answer 25

Rods: Have most of these, Most sensitive to light, Sides of eye
Cones: Color, center of eye, works best in bright light

Question 26

What is the blind spot?

Answer 26

The spot in your eye with no rods and cones since it is the entrance of the optic nerve

Question 27

What is the optic disc? What kind of photoreceptors are found there?

Answer 27

Location at back of eye where axons of ganglion cells leave eye. No photoreceptors

Question 28

What is glaucoma?

Answer 28

Condition where aqueous humor is drained slower than it is produced

Question 29

What is another term for nearsightedness? What can cause this?

Answer 29

Myopic eye -> Eye may be too long, image focuses in front of retina

Question 30

What is presbyopia?

Answer 30

Lens becomes less elastic with age—need bifocals

Question 31

What happens with astigmatism?

Answer 31

Abnormal shape of corneal surface causes light rays to diffract differently

Question 32

What is a cataract?

Answer 32

Lens becomes cloudy -> Most commonly due to age-related damage to the internal part of lens

Question 33

What is the structure of the ear that is easily seen?

Answer 33

External ear

Question 34

What are the glands that produce ear wax?

Answer 34

Ceruminous glands and sebaceous glands

Question 35

The middle ear lies between what two structures?

Answer 35

The middle ear extends from the tympanic membrane to oval window

Question 36

What are the ossicles, in order, as you move deep into the ear?

Answer 36

Malleus, Incus, Stapes

Question 37

What connects the middle ear with the pharynx?

Answer 37

Pharyngotympanic tube

Question 38

What are the muscles that dampen loud noises? What are they attached to?

Answer 38

Tensor tympani -> attaches to malleus
Stapedius -> attaches to stapes

Question 39

What is a myringotomy?

Answer 39

A tube used to drain fluid in ears into throat

Question 40

What are differences between the bony and membranous labyrinths?

Answer 40

Bony: Cavity in the petrous portion of temporal bone
Membranous: Continuous series of membrane-walled sacs
and ducts that fit loosely within bony labyrinth

Question 41

What kind of fluid fills the membranous structures? The bony labyrinth?

Answer 41

Bony: perilymph
Membranous: endolymph

Question 42

What are differences between inner hair cells and outer hair cells?

Answer 42

Inner hair cells: True receptors, transmit vibrations of basilar membrane to cochlear nerve
Outer hair cells: Tune and amplify signal (100X), Helps us hear faint signals, Can produce otoacoustic emissions, Used to test hearing in newborns

Question 43

Where in the cochlea do high pitched sounds deflect the basilar membrane? Low pitched sounds?

Answer 43

• Low pitch (low frequency) sounds deflect deep into cochlea
• High pitch (high frequency) sounds deflect near entrance of cochlea

Question 44

Which structure (utricle or saccule) is involved to vertical movements?

Answer 44

Saccule

Question 45

What are otoliths and how are they involved with equilibrium?

Answer 45

Calcium carbonate crystals that add weight to membrane and cause more dramatic shift

Question 46

What kind of stimuli do the semicircular canals respond to?

Answer 46

Are involved with rotational acceleration of the head

Question 47

What structure in the semicircular canals has receptors?

Answer 47

crista ampullaris

Question 48

What is vertigo and what can cause it?

Answer 48

feeling of motion when you aren’t moving
* Alcohol consumption changes viscosity of endolymph
* Infection (viral or bacterial)
* Otolith from maculae can become dislodged and eventually end up near crista ampullaris where they impact cupula function

Question 49

What is the vomeronasal organ? What does it respond to?

Answer 49

Pheromone sense in nose