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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
