PHYS II - Exam I, Part II (Special Sensation)

Which of the photoreceptors responds to light in 3 different wavelength ranges?

cones

Which photoreceptor has a low threshold and is the most sensitive to low levels of light?

rods

Which photoreceptor has a high threshold and responds to large changes in light?

cones

Which photoreceptor would function well in bright/daylight conditions?

cones

Which photoreceptor has low acuity?

rods

T/F? Cones are more numerous than rods

False! rods more numerous than cones

What are the 3 wavelength color ranges (photopsin) associated with cones?

red, blue, green

Which photoreceptor has high acuity?

cones

Where is the area of the highest concentration of cones?

fovea

T/F? There is 1 rod per bipolar cell

False - 1 cone per bipolar cell so high acuity

many rods per bipolar cell so low acuity

The iris has 2 muscles, which increases the size of the pupil?

dilator AKA radial

The iris has 2 muscles, which decreases the light coming into the eye?

sphincter (constricts the pupil)

T/F? Photons of light must pass through the cornea and the lens before striking photoreceptors of the retina

True

Light has to pass through all layers before striking the most ________ cellular layer of what type of cells?

posterior layer

pigmented cells

Which of the following is NOT a structure that light passes through on its way to the retina?

a. cornea

b. iris

c. lens

d. vitreous humor

B. iris

Which cell type are epithelial cells with melanin to help absorb light?

pigmented

How many layers of cell must the retinal cells pass through the reach the pigmented cells?

5

Which cell type relay info to the ganglion?

bipolar cells

Which cell type has axons that make up the optic nerve?

ganglion cell

Which cells process the image and provide lateral inhibition?

horizontal cells

Which cells communicate with bipolar and ganglion cells?

amacrine cells

T/F? Horizontal cells help with passing the image along

False - processing ONLY

What is the order or transmission between neuronal layers of the retina starting with visual signal...

photoreceptor

bipolar

ganglion

axons to CN (exit eye)

T/F? Visual images from the temporal field of view cross at the optic chiasm

True

What is visual transduction?

conversion of light energy to electrical signals

Visual transduction occurs when light strikes a photoreceptor and...

hyperpolarizes

no glutamate released (inhibitory)

stimulates bipolar cells which stimulate ganglion cells

Are channels open or closed when light strikes a photoreceptor?

closed, no influx of (+)

Visual transduction does NOT occur when... (hint: dark)

depolarizes

releases glutamate (inhibitory)

bipolar cells inhibited

Rods have what photosensitive pigment protein?

rhodopsin

Cones have what photosensitive pigment protein?

photopsin

Do rhodopsin and photopsin hyperpolarize or depoalrize the cell?

What does this do to channels?

hyperpolarize

closes channels

Once vision reaches the ganglion cells, what do the ganglion axons form?

each optic nerve

The visual information exits the eye at what feature?

optic disc

Where does visual information synapse?

lateral geniculate nucleus of thalamus

Where does visual information ultimately end up?

calcarine sulcus of occipital lobe

AKA primary visual cortex

The temporal visual field will hit the...

nasal retina

T/F? The nasal visual field crosses at the optic chiasm

False! Does NOT cross

The nasal visual field will hit the....

temporal retina

The lateral rectus extraocular eye muscle is supplied by...

CN 6

The superior oblique extraocular eye muscle is supplied by...

CN 4

All extraocular eye muscles except for lateral rectus and superior oblique are supplied by...

CN 3

A convex lens does what to light?

Concave?

convex = focuses

concave = diverges

Hyperopia is known as nearsighted or farsighted?

farsighted

Myopia is known as nearsighted or farsighted?

nearsighted

What is refraction like in an individual with hyperopia?

refraction too weak

What lens is used to correct hyperopia?

convex

What is refraction like in an individual with myopia?

refraction too strong

What lens is used to correct myopia?

concave

Where is the point of focus in hyperopia?

behind retina

Where is point of focus in myopia?

in front of retina

Where are hair cells located?

organ of corti

Which structure houses the site of auditory transduction, the organ of corti?

scala media

Where is scala media found?

1 of 3 tubular canals of cochela

When sound is being processed, first vibrations hit what membrane?

tympanic

Which structure increases the force of sound vibrations 22x what was present at tympanic membrane...

auditory ossicles

The auditory ossicles pass the vibration to what structure next?

oval window

The vibrations travel from oval window to WHAT specifically in the cochlea?

perilymph (scala vestibuli)

High frequency is associated with high _________

pitch

Low amplitude is associated with low ________

volume

T/F? Amplitude is independent of frequency

True

What are the 3 chambers of the cochlea?

scala vestibuli

scala media

scala tympani

The basilar membrane is associated with which chamber of cochlea?

scala media

What lies on top of the basilar membrane? What is it made up of?

spiral organ of corti

hair cells

The thickness and level of stiffness of the _______ accounts for the ability to process sounds at varying pitches/frequencies

basilar membrane

The inner portion of organ of corti is sensory or motor?

Outer portion?

inner = sensory

outer = motor

Concerning the spiral organ (of Corti), which of the following is an immobile membrane that the stereocilia of the hair cells are attached to?

tectorial

T/F? The base of the basilar membrane is tuned to low frequency of ~20 hz

False - apex = 20,000 (high frequency)

The apex of the basilar membrane allows for ______ hz

20 hz (low frequency)

The scala vestibuli and scala tympani communicate with what structure?

helicotrema

The scala medi and scala tympani communicate via what?

basilar membrane

If sound is low enough frequency that the basilar membrane is never affected, then what structure does transduction not occur around?

helicotrema

What is the hearing range for healthy ears?

20-20,000 Hz

What is the hearing range for presbycusis (older age)?

50-8,000 Hz

Bending of stereocillia of the hair cells causes what to happen?

depolarization, influx of K+ (action potentials sent)

A large amplitude would mean how many K+ channels to open?

large amplitude = large K+

A small # of K+ receptor channels opening would mean what for the receptor potential?

Which CN are these action potentials sent?

small receptor potential

CN 8

Endolymph is rich in ______ when compared to perilymph

K+

When hair cells depolarize, what do they release?

Which CN is stimulated?

glutamate

CN 8 (auditory)

T/F? Auditory signals reach ONE side of the thalamus and cortex

FALSE - reach both sides of thalamus and cortex b/c some fibers cross, some do not

Concerning the auditory pathway, which of the following is the origin of the neurons ( not the origin of the signal) that will synapse in the medial geniculate nucleus of the thalamus?

inferior colliculus of midbrain

Concerning the auditory pathway, 4th order neurons ascend to synapse on the ________ geniculate nucleus

medial

The vestibular apparatus is made up of what 3 parts?

utricle

saccule

semicircular canals

Linear equilibrium is transduced in the...

utricle and saccule

The utricles and saccules have what kind of specialized membrane for reference/pull of gravity?

otolithic membrane

When stereocilia bend TOWARD the kinocillium, what happens?

excitatory, opens K_ channels, depolarize

When stereocilia bend AWAY from the kinocillium, what happens?

inhibitory, no K+

Which vestibular apparatus feature is involved in horizontal acceleration and deceleration?

utricle

Which vestibular apparatus feature is involved in vertical acceleration or up/down movement?

saccule

T/F? BOTH utricle and saccule are affected by gravity

True

Angular dynamic equilibrium is transduced in the...

semicircular canals

T/F? Semicircular canals are affected by gravity

False - no otholiths

The ________ in the semicircular canals houses hair cells

crista ampullaris

Mechanical deformation of hair cells triggers what?

opening of K+ channels so depolarization

What is moved according to movement of head in any of the 3 planes?

endolymph (fluid)

The anterior semicircular duct is in the ______ plane and is involved with what movement?

sagittal

flexion/extension

The posterior semicircular duct is in the ______ plane and is involved with what movement?

coronal

lateral bending

The lateral semicircular duct is in the ______ plane and is involved with what movement?

horizontal

rotation left/right

Which semicircular duct is the most commonly effected in vertigo (90%)?

posterior

Which CN are associated with vestibular pathway?

CN 3, 4, 6 (eyes) and CN 11 (head and neck)

Spinning room or self dizziness is likely associated with what kind of issue?

central or peripheral vestibular issue