Senses – Vision included (final) Flashcards
1
Q
What is the physical manifestation of sound intensity?
A
Difference in pressure between compressed and rarified patches within the medium.
L9a #6
2
Q
Give the medium of conduction for:
- ) Outer ear
- ) Middle ear
A
1.) Outer ear = Conduction through AIR
2.) Middle ear = Conduction through BONE
L9a #10
3
Q
What are the conducting and neural components of the ear?
A
Conducting: Outer and middle ear
Neural: Inner ear – Cochlea and Spiral ganglion
L9a #9
4
Q
What is the modiolus and what does it contain?
A
Modiolus is the bony core of the cochlea, it contains the beginnings of CN VIII (vestibulocochlear nerve).
L9a #14
5
Q
What comprises the bony labyrinth and membranous labyrinth of the cochlea and what fills them?
A
Bony labyrinth: Scala vestibuli and scala tympani (perilymph-filled).
Membranous labyrinth: Scala media (endolymph-filled).
L9a #16
6
Q
When the stapes pushes on the oval window, which cochlear cavity/compartment is first to feel the perturbation in fluid?
A
Scala vestibuli —> Directly connected to the oval window.
L9a #16
7
Q
Where are the scala vestibuli and scala tympani continuous with one another?
A
A point at the apex of the cochlea called the Helicotrema
L9a #17
8
Q
- ) Give the relative Na+ and K+ ionic concentration within perilymph. What other bodily fluid does it resemble in composition?
- ) What feature of perilymph makes it ideal for its role in sound transduction?
- ) What additional structural feature aids #2?
A
1.) High Na+ and Low K+. Composition similar to CSF.
2.) Perilymph is INCOMPRESSIBLE
3.) Bony labyrinths (outside of cochlea) are also incompressible.
L9a #17
9
Q
- ) The stereocilia of hair cells project into what?
2. ) What are they embedded in?
A
1.) Endolymph of the scala media
2.) Embedded in the Tectorial membrane
L9a #19
10
Q
Concerning the auditory hair cells, what are their names “inner” and “outer” in relation to? Explain.
A
In relation to their relative distance from the modiolus (bony core of the cochlea).
Inner hair cells: Closer to the modiolus.
Outer hair cells: Further from the modiolus
L9a #19
11
Q
- ) What characteristics of hair cells movement/displacement are responsible for Amplitude/Intensity and Frequency?
- ) What do these characteristics translate into in terms of sound qualities?
A
1.) Amplitude/Intensity: Degree of hair cell displacement.
Frequency: How quickly/repeatedly they are moved.
2.) Amplitude/Intensity = Loudness
Frequency = Pitch
L9a #20
12
Q
What are the inner and outer hair cells best for detecting?
A
Inner hair cells: Frequency detection.
Outer hair cells: Amplitude detection.
Mnemonic: “IF Only” —> Inner = Frequency
L9a #21
13
Q
What amplifies the signal created by hair cells (2)?
A
Signal amplified by ionic content of endolymph and by outer hair cells.
L9a #20 and 22
14
Q
Describe the two portions of the basilar membrane in terms of stiffness/width and frequency detection
A
Base: Narrower and more rigid/stiff; detects high frequencies.
Apex: Wider and more compliant; detects low pitches.
Higher frequencies detected at the entrance and exit points for the perilymph-containing scala (near the round and oval windows)
L9a #22, p.289 Haines
15
Q
Where does the basilar membrane vibrate (in general terms)?
A
Where the frequency finds a sympathetic response.
L9a #22
16
Q
What is the frequency range of the basilar membrane?
A
20-20,000 Hz
L9a #22
17
Q
What is found in the spiral ganglion?
A
Cell bodies of the first order neurons in the auditory pathway.
The only neurons in the PNS for audition
18
Q
Describe the neurons of the auditory pathway in terms of:
- ) Neuron type
- ) Their processes (where they are and what nerves they form).
A
1.) Bipolar neurons
2.)
(i) Central processes: Collectively the cochlear/acoustic nerve.
Comprises part of CN VIII
(ii) Peripheral processes: Collectively the auditory nerve. Synapse with hair cells
L9a #25
19
Q
- ) Which cochlear compartment contains the organ of corti?
2. ) What are the hair cells in the organ of corti innervated by?
A
1.) Scala media
2.) Peripheral processes of the bipolar neurons.
L9a #25-26
20
Q
- ) What does the Weber test evaluate?
- ) What implement is used for the test and how?
- ) Damage to which structures gives positive test (2)?
- ) What findings constitute a positive test?
A
1.) Evaluates for Sensorineural hearing loss i.e. differentiates between conductive and sensorineural hearing loss.
2.) Use a tuning fork (vibrating at 256 or 512 Hz) place somewhere ALWAYS ON THE MIDLINE, e.g. middle of forehead, above upper lip (under nose), or on top of head equidistant from ears.
3.) Auditory nerves or hair cells
4.) Normal ear hears sound better (normal patient has equal volume in both ears).
L9a #28
21
Q
- ) What does the Rinne test evaluate?
- ) What implement is used for the test and how?
- ) What findings constitute a positive Rinne test?
- ) Affected patient?
A
1.) Conductive hearing loss (air or bone conduction).
2.) Tuning fork (vibrating at 512 Hz) on skin overlying mastoid process (bone conduction) and outside ear (on the pinna – air conduction) Note time until tone is no longer detected at each site.
3.) Detection outside ear > Detection on initial mastoid site
-Positive Rinne test is a NORMAL PATIENT!
4.) Detection on initial mastoid site > Detection outside ear
L9a #29
22
Q
How is hearing loss measured on an audiogram?
A
Measured as the volume needed to detect a sound at a particular frequency.
L9a #38
23
Q
What is the decibel range of human speech?
A
20 to 50-60 dB
L9a #39
24
Q
What five spoken letters require the greatest volume to be heard/distinguished?
A
E, N, O, U, G mnemonic —> ENOUGh
L9a #39
25
What decibel level heard for 8 hours per day is likely to cause hearing loss?
≥ 85 dB
| L9a #39
26
1. ) Noise-induced hearing loss (a ______ cause) is characterized by hearing loss at ___________.
2. ) What type of pain and/or visible trauma is evident?
3. ) __________ with each exposure
1.) -A progressive cause
-Select frequencies
2.) No pain or visible trauma
3.) Accumulates with each exposure
L9a #40
27
1. ) What is the term for age-related hearing loss?
2. ) What range of detection is the first to go/most severe (in terms of pitch/frequency and position on basilar membrane)
3. ) Give (i) two primary and (ii) three secondary symptoms
1.) Presbyacusis
2.) Higher pitches/frequencies (base of basilar membrane).
3.) (i) Loss of directionality, difficulty understanding speech. (ii) Hyperacusis (sensitivity to volumes or frequencies), tinnitus, vertigo.
L9a #42
28
What are three criteria for cochlear implants?
1.) Severely hard of hearing (particularly in the low frequencies).
2.) People who *lost their hearing* (i.e. beyond their critical period) and have DAMAGED HAIR CELLS (i.e. not congenital, because in that case, the correct neural framework never would have had a chance to be set up).
3.) Children BEFORE they have passed through the *critical period* for audition (i.e. retain some neuroplasticity for audition).
L9a #43
29
Where are cochlear implants placed?
On the auditory nerve
| L9a #43
30
Where is a neural hearing implant placed?
Directly in the space of the cochlear nuclei (where it electrically stimulates the neurons in the cochlear nucleus).
*Not a effective as a cochlear implant at this point*
L9a #47
31
Describe the ascending auditory pathway starting with the termination of the 1st order cochlear nerve fibers. Give CNS level/location for each of the FIVE components (one of them is an dual route, so there are technically FOUR levels).
1.)
(a) Cochlear nuclei (medulla-pons): Only auditory nuclei that does not receive binaural input.
*AND*
(b) Superior olivary nucleus (pons): Input from ventral cochlear nuclei. There are two of them – medial and lateral olivary nuclei.
2.) Inferior colliculus (midbrain)
3.) Medial geniculate nucleus (thalamus)
4.) Auditory cortex (cerebral cortex)
L9a #49, p.205 BRS
32
1. ) The inferior colliculus is part of the ______ of the ________.
2. ) In other words, it is the _______ component of the ___________ in the _________.
1.) Part of the TECTUM (aka roof plate) of the midbrain.
2.) Caudal component of the *quadrigeminal plate* in the midbrain (#55).
L9a #49
33
1. ) What are the external manifestations of the posterior acoustic striae and where are they?
2. ) What is unique about this pathway?
3. ) This is part of what set of pathways?
1.) Striae medullares on the surface of the rhomboid fossa (dorsal medulla).
2.) It bypasses the superior olivary nucleus and goes straight to the inferior colliculus.
3.) Medullopontine pathways
L9a #50
34
1. ) Where does the Medial Superior Olivary Nucleus receive inputs from?
2. ) What is its main function?
1.) Receives inputs from left side OR crossing input from the right side.
2.) Measures time difference/difference in how quickly the SAME sound message reaches the superior olivary nucleus, i.e. helps LOCALIZE SOUND.
Mnemonic —> *M*edial = *M*inutes (of time difference —> localize)
L9a #52
35
What is the function of the Lateral Superior Olivary Nucleus?
Measures the difference in SOUND INTENSITY (loudness) between the two ears.
Mnemonic —> *L*oudness = *L*ateral
L9a #52
36
The superior olivary nucleus is the first place for what?
First place where there is a mixing of information of one side versus the other (i.e. first place where there is BINAURAL INFORMATION).
L9a #52
37
Describe how the stapedius muscle is activated (i.e. connections). What is this for?
Cochlear nuclei —> Superior olivary nuclei (bilaterally) —> Facial nucleus —> Facial nerve to stapedius.
*Connections to dampen loud sounds for hair cell protection*
L9a #53
38
Define lemniscus
2nd order crossing fibers
| L9a #54
39
Describe the lateral lemniscus, i.e. what type of fibers, and where to/from
2nd order fibers from cochlear nuclei directly to the CONTRALATERAL inferior colliculus.
L9a #54
40
What is the common organizational pattern of tones in the superior olivary complex, the trapezoid body, and the inferior colliculus?
Low tones = Lateral
High tones = Medial
L9a #63-64
41
1. ) What are the afferents and efferents for the medial geniculate nucleus (give laterality)?
2. ) What is its function, i.e. what information does it carry (4)?
1.) Afferent: Ipsilateral inferior colliculus, ipsilateral auditory cortex.
Efferent: ipsilateral Auditory cortex
2.) Carrying frequency, intensity, and binaural (FIB) information to cortex (BUT...the first place to have binaural information is the superior olivary nucleus).
L9a #59
42
The vestibular system detects ______ and ______ of the _______.
Detects position and movement of the head.
| L9b #7
43
1. ) Describe the adaptation speed of the vestibular system and why it must be this way
2. ) Firing rates of neurons change in response to what?
1.) Rapidly adapting because it detects changes over time.
2.) In response to movement
L9b #7
44
Which two parameters of position and movement does the vestibular system detect?
*Attitude* and acceleration
| L9b #7
45
Endolymph is a fluid designed to facilitate _________.
Synaptic transmission
| L9b #9
46
Bending of the cupula within the ampulla is caused by a change in ________.
Angular acceleration.
| L9b #10
47
The two otolith organs are designed to detect __________.
Linear acceleration.
| L9b #11
48
Describe the two otolith organs in terms of their macule orientation, hair cell orientation, and what they respond to. How are the otoliths oriented to one another?
-Utricle: Horizontally-oriented macule, vertically-oriented hair cells. Responds to movement parallel to the ground.
-Saccule: Vertically-oriented macule, horizontally-oriented hair cells. Responds to vertical movements (against or with gravity).
*Oriented at right angles to one another*
L9b #11
49
1. ) Within the otoliths, movement of the ________ imparts the sense of motion (i.e. transduces signal).
2. ) The region of otolith organs containing hair cell receptors is called what?
1.) Kinocilia
2.) Macula
L9b #12
50
1. ) What type of hearing loss is associated with Meniere's disease?
2. ) What hearing would be used?
3. ) The initial hearing loss occurs in ______ frequencies.
4. ) What does the audiogram look like in advanced stages?
1.) Sensorineural (not conductive)
2.) Weber test
3.) *Lower* frequencies, but continues to middle and high frequencies as the disease progresses.
4.) Becomes flat or falling.
L9b #17
51
1. ) What is the 1˚ pathophysiological feature of Meniere's disease?
2. ) Where is pressure transmitted?
3. ) What are the four principal symptoms?
1.) Hydrops – increased endolymph fluid and pressure in the endolymphatic sac.
2.) To the Cochlear *duct*, because endolymph is incompressible.
3.) Pressure/feeling of fullness in the ear, tinnitus, recurring vertigo, hearing loss
L9b #16, 21
52
The pressure/swelling associated with Meniere's disease distorts what four structures?
1.) Reissner's membrane
2.) Scala media
3.) Semicircular canals
4.) Otolith organs
*Both 1-2, and 3-4 go together*
L9b #21
53
1. ) Where are the cell bodies for the bipolar vestibular neurons found (two names)?
2. ) Describe the connection between the two
1.) Vestibular ganglia (VG), aka Scarpa's ganglion
2.) Peripheral processes from the bipolar neurons extend from the hair cells in the end organs (otoliths or semicircular canal) to the cell body in the VG.
L9b #24
54
Name the two vestibular ganglia and which vestibular receptors they control.
Superior VG: Anterior and horizontal semicircular canals, and utricle.
*Think "everything in front of you —> Anterior + Horizontal x2*
Inferior VG: Posterior semicircular canal and saccule.
*Posterior and vertical*
L9b #24
55
1. ) Where are the second order neurons of the vestibular system located?
2. ) Where do they receive direct innervation from?
1.) Four vestibular nuclei located in the lateral medulla.
2.) Receive direct innervation from the 1st order neurons in vestibular (spiral) ganglia.
L9b #29
56
3rd order neurons of the vestibular system receive projections from the _________.
Vestibular nuclei.
| L9b #31
57
1. ) How do projections from the 2nd order neurons in the vestibular nuclei *ascend* to reach their 3rd order nuclei (i.e. where do they travel)?
2. ) What are the two end-locations for ascending vestibular nuclei projections?
3. ) What are two other non-ascending end-locations (one is a descending pathway)
1.) via the MLF (medial longitudinal fasciculus).
2.) Oculomotor muscles (particularly CN III and VI; responsible for lateral eye movements) and Thalamus.
3.) Cerebellum, and spinal cord (via lateral and medial vestibulospinal tract).
L9b #31
58
For the lateral vestibular tract:
1. ) Origin
2. ) Structures it passes through (2)
3. ) Termination
4. ) What it regulates
1.) Lateral vestibular (Dieter's) nucleus.
2.) *Anterior funiculus* and inferior vestibular nuclei
3.) Ipsilateral anterior horn on α and γ motor neurons.
4.) Regulates position-related musculature (anti-gravity muscles), i.e. extensors + back and lower limb muscles.
L9b #31
59
For the medial vestibular tract:
1. ) Origin
2. ) Structures it passes through (1)
3. ) Termination
4. ) What it regulates
1.) Medial vestibular nucleus
2.) Anterior funiculus
3.) Bilateral anterior horn on α and γ motor neurons of CERVICAL and THORACIC cord.
4.) Regulates HEAD POSITION-related musculature.
L9b #32
60
1. ) Where is the primary vestibular region in the cortex, i.e. what site of cortex receives most vestibular input?
2. )
```
Area 3 (related to the face), and places where vestibular input mixes with other modalities.
L9b #33
```
61
Vestibulo-ocular reflex (VOR) requires that the vestibular nuclei be connected to what two things?
```
CN III (oculomotor) and CN VI (abducens)
L9b #35
```
62
Be able to explain the "Testing Vestibular Function" on #35 of L9b
poop (L9b #35)
63
1. ) Describe the ocular effects of pouring cold vs warm water into a persons ear canal.
2. ) What is this procedure called?
3. ) How does this relate to nystagmus?
1.) Cold water = eyes turn in the direction of the ear into which cold water was poured.
Warm water = eyes turn in the direction opposite of the ear into which warm water was poured.
2.) Caloric test of vestibulo-ocular reflex.
3.) With nystagmus, there is the same effect, but...
The eyes move *slowly* in the initial direction as detailed above, then *quickly* move back in the opposite direction.
L9b #36
64
What does the caloric test of vestibulo-ocular reflex evaluate in unconscious or comatose patients?
Tests for competence of *brainstem* and pathways.
| L9b #37
65
1. ) In a patient with a bilateral MLF lesion, what would be the result of a caloric test of vestibulo-ocular reflex using cold water on the right side?
2. ) Low brainstem lesion?
1.) Only the eye on the right side (side into which water was poured) will respond normally. The contralateral eye will only be able to go to the midline, at which point *it will exhibit NYSTAGMUS (snap back in the opposite direction).*
2.) Low brainstem lesion = No change on caloric test
L9b #37
66
The olfactory bulb is part of the ______ lobe
Frontal
| L9c #6
67
Which part of the cortex is related to the uncus and other olfactory components?
Piriform cortex
| L9c #7
68
What four things are found in the olfactory lamina propria?
Bowman's glands (extends into basal lamina), olfactory axons, blood vessels, other somatic afferents (pain, touch, temp., etc).
L9c #9
69
What is the thinnest and most slowly-conducting nerve in the entire nervous system?
Basal axons of the olfactory receptors
| L9c #11
70
1. ) All receptors associated with olfaction are what type of receptors?
2. ) How are they activated (i.e. what activates them...two things), and what is the subsequent cascade of events?
1.) G protein-coupled receptors
2.) Odorant molecule binds odorant-binding protein in the mucus. This complex then binds G protein-coupled receptor = 2nd messengers (cAMP or IP3) —> opens cation channel = depole....OR —> Ca2+ gated Cl- channels open —> Generator potential
L9c #15
71
Where are the G protein-coupled receptors located in the olfactory neurons?
In the apical dendrites
| L9c #16
72
What three characteristics of olfactory neurons allow for a receptor map to be constructed (i.e. allow for odorant specificity)?
1.) Selective expression of receptors in specific neurons.
2.) Selective projection to glomerulus in olfactory bulb.
3.) Neural convergence.
L9c #20
73
1. ) Which two cells carry out lateral inhibition in the olfactory system?
2. ) What is the purpose of this?
1.) Granule and periglomerular cells.
2.) Sharpens and focuses the olfactory signals.
L9c #20
74
List the six cell layers of the olfactory bulb from outside to inside, and what cells/important structures are present in those specific layers.
(1) Olfactory epithelium (w/ olfactory neurons) —Cribiform plate—> (2) Olfactory nerve layer (w/ olfactory neurons) —> (3) Glomerular layer (olfactory glomerulus and periglomerular cells) —> (4) External plexiform layer (tufted cells) —> (5) Mitral cell layer (Mitral cells) —> (6) Granule cell layer (Granule cells, centrifugal fibers).
L9c #18
75
1. ) List the which cells/fibers have excitatory (4) and inhibitory (1) effects on the olfactory glomerulus.
2. ) Which NTs do each use – excitatory (2), inhibitory (1)?
1.) Excitatory: Axons of bipolar neurons, dendrites of mitral and tufted cells, and centrifugal *afferents*.
Inhibitory: Dendritic tree of periglomerular cells.
2.) NTs
Excitatory: Glutamate, *carnosine*
Inhibitory: GABA
L9c #19
76
What are the smallest cells within the olfactory bulb? What is their characteristic feature that sets them apart from the rest?
```
Granule cells (interneurons); they have *NO AXON*
L9c #22
```
77
From which cells do olfactory efferents arise (2) and where do they go?
Efferent projections from MITRAL and TUFTED cells —> to the lateral olfactory tract.
L9c #18 and 23
78
1. ) List the two parts of olfactory cortex, along with the two subdivisions of each. What is the function at this level?
2. ) Histologically, what type of cortex is this considered?
3. ) What is the function at this level?
1.) (i) Anterior part: Olfactory tubercle, piriform cortex.
(ii) Posterior part: Periamygdaloid cortex, entorhinal cortex.
*No smell discrimination at this level, i.e. you know you smell something, but you don't know what it is*
2.) Paleocortex
3.) Just detection of odor, no discrimination.
L9c #25
79
Where in cortex does interpretation/identification, discrimination, and integration of olfactory stimulus occur (2)?
Ventral insular and *orbitofrontal* (orbital) cortex.
*Both are neocortex*
L9c #26
80
What roles do the Lateral Hypothalamus and Hippocampus play in olfaction?
Lateral hypothalamus: Feeding behavior; autonomic responses.
Hippocampus: Learning and behavior – i.e. OLFACTORY MEMORIES.
L9c #27
81
Unique properties:
1. ) Olfactory receptors are true _____.
2. ) Neuronal processes are __________.
3. ) Ability to ______ neurons.
4. ) Sensory pathway reaches cerebral cortex without ________.
1.) True neurons
2.) Exposed to the surface (nowhere else does this happen)
3.) Ability to regenerate neurons
4.) Relay in the thalamus
L9c #28
82
Fracture of what structure(s) can cause anosmia?
Fracture of anterior cranial fossa (in relation to the cribiform plate).
L9c #30
83
Describe Foster-Kennedy syndrome (with three symptoms)
*Frontal lobe tumor* that causes increased intra-cranial pressure, resulting in:
1.) Anosmia
*2.) Contralateral papilledema*
*3.) Ipsilateral optic atrophy*
L9c #31
*Papilledema is optic disc swelling that is caused by increased intracranial pressure (wiki)*
84
What is olfactory agnosia?
Perception of smell is intact, but odor recognition is lost.
L9c #33
85
Which lingual papillae have no taste buds?
Filiform papillae.
| L9c #36
86
1. ) Give the CN associated with each of the three papillae with taste buds.
2. ) What CNs are associated with taste for the epiglottis and soft palate?
1.)
(i) Fungiform – CN VII
(i) Foliate – CNs IX and VII
(iii) Circumvalate – CN IX
2.) Epiglottis – CN X, Soft palate – *CN VII*
L9c #36
87
1. ) Which lingual papillae have taste buds on the side/cleft (2)?
2. ) What helps dissolve the tastants (taste substance) within the cleft?
3. ) Which lingual papillae have taste buds on the top surface?
1.) Foliate and circumvallate
2.) Von Ebner's glands
3.) Fungiform
L9c #37
88
Concerning Type II taste cells:
1. ) What type of cells
2. ) Receptor type
3. ) Taste sensations encoded (3)
4. ) Special feature
1.) Receptor/Neuroepithelial cells
2.) G protein-coupled receptors
3) Bitter, sweet, umami
4.) Secrete ATP to stimulate Type III cells.
L9c #41
89
Concerning Type III taste cells:
1. ) What type of cells
2. ) Receptor type
3. ) Taste sensations encoded (2)
4. ) Special feature
1.) Presynaptic cells with synaptic vesicles
2.) Cation channels
3.) Salt and sour
4.) *Release serotonin and norepinephrine*
L9c #41
90
What types are cells are Type I and Type IV taste cells?
Type I: Supporting/Glial cells
Type IV: Basal cells
L9c #41
91
What chemical compounds are responsible for the five taste sensations?
```
Sweet: Glucose or similar compounds
Sour: Acidic
Salty: Ionic compounds
Bitter: Alkaloids
Umami: Glutamate
L9c #43
```
92
What type of receptors are responsible for the five taste sensations and how are they transduced?
1. ) Salt and sour: Ionotropic receptors/ligand-gated channels.
- Salt: Cation channel; Na+ entry
- Sour: H+ blocks outward K+ current, increasing the positive potential inside the cell, resulting in AP.
2. ) Sweet, bitter, and umami: G protein-coupled receptors.
- Sweet and Bitter: G protein-coupled receptor —> 2nd messengers (cAMP/IP3) —> Increased Ca2+ (releasing NT)... OR it *blocks K+ channel*
-Umami: Glutamate receptor —> G protein-coupled *phosphodiesterase* —> *DECREASED cAMP*
L9c #44-45
93
1. ) What is the neural component of the 1st order taste neurons?
2. ) Where are the cell bodies for the 2nd order neurons?
3. ) Describe the two parts of #2 above
1.) SVA
2.) Nucleus solitarius (solitary tract nucleus)
3.)
(i) Gustatory part (SVA): Rostral (upper part)
(ii) Visceral part (GVA): Caudal – cardiorespiratory
L9c #49
94
What are the two efferents for the Solitary Tract Nucleus
1.) Central tegmental tract to the VPMpc thalamus (taste center in thalamus).
2.) *Medullary reflex center* – autonomic reflexes associated with taste (e.g. salivation, swallowing, choking, etc.).
L9c #49
95
1. ) Where are the 3rd order neurons in the taste pathway?
2. ) Where do they project?
3. ) What is the function of #2?
1.) VPMpc thalamus
2.) Projects to the IPSILATERAL frontal operculum, anterior insular cortex, *AREA 3b*
3.) Discriminates taste sensation.
L9c #50
96
What is the secondary projection for the third order neurons of the taste pathway? Function?
Orbitofrontal cortex (just like the olfactory pathway).
Function: Integration with olfaction.
L9c #50
97
# Define:
1. ) Dysgeusia/Parageusia
| 2. ) Cacogeusia
1.) Altered taste sensation
2.) Typically good things taste bad
L9c #53
98
Describe Vestibular Schwannoma – Cause and three symptoms.
Tumor associated with vestibular nerve (CN VIII) at the *cerebello-pontine angle* can compress the adjacent FACIAL NERVE (CN VII).
-Loss of taste in *anterior 2/3 of tongue*
-Facial nerve palsy
-Hearing loss
L9c #54
99
What are the four refractive elements, and the two non-impeding elements we use to collect and conduct information with the eye?
Refractive: Cornea, lens, iris, pupil
Non-impeding: Aqueous and vitreous humor
L8a #7
100
What comprises the outer fibrous (2) and middle vascular (4) layers of the eye?
Outer fibrous: Cornea and sclera
Middle vascular: Uvea – choroid, ciliary body, iris...lens (?)
L8a #9
101
What produces the lipids found in tears?
Meibomian glands —> mucin-associated (not sure if this means a different source, or if the lipids produced in Meibomian glands are mucin-associated).
L8a #10
102
Compare the electrolyte content of tears to that of plasma
The [Na+] of tears ≈ [Na+] of plasma
| L8a #10
103
1. ) What three types of enzymes are found in tears?
2. ) Which three types of immunoglobulins are found in tears?
3. ) Which three radical scavengers are found in tears?
1.) Lysozyme, peroxidase, glycosidase
2.) IgA, IgE, IgG
*Complement also found in tears*
3.) Ceruloplasmin anti-complement, Ascorbate, Lactoferrin *CAL —> Think radiCAL*
L8a #10
104
What type of gland is the lacrimal gland? What glandular component do they NOT contain?
Tubuloacinar gland with serous acini, but does have intra- and interlobular ducts.
*Does not contain STRIATED DUCTS.*
L8a #11
105
What type of innervation does the lacrimal gland receive and what are the ganglia?
SNS: Superior cervical ganglion.
PSNS: Facial nerve (1st order) —> Pterygopalatine ganglion (2nd order).
L8a #11
106
1.) Concerning the two muscles of the eyelid, which is more superficial and which is more deep? 2.) How are they oriented to one another?
1.) The Obicularis oculi is more superficial (closer to the skin surface), and the Levator palpebrae superioris is deeper (closer to tarsal plate and conjunctiva).
2.) Orbicularis is a sphincter muscle (round), and levator is longitudinal.
L8a #12
107
1. ) What is the eye's chief refractive element?
| 2. ) Describe the vascularity and innervation of the component
1.) Cornea
2.) Avascular, richly innervated
L8a #14
108
What is the first refractive element light contacts on/within the eye?
Tears
| L8a
109
Impairment of what may lead to age-related macular degeneration?
Oxygen supply to the choroid/uvea
| L8a #18
110
Changes in _____ more the retina forwards and backwards. What effect does this have?
Changes in choroid thickness move the retina forward and back. This affects the relationship of photoreceptors to the plane of focus – an issue for myopia and hyperopia.
L8a #18
111
Describe the vascularity and innervation of the ciliary body.
Highly vascular and richly innervated.
| L8a #21
112
What two structures within the ciliary body stroma are critical to the function of the eye and why?
1.) Melanocytes: Traps errant light; helps to increase acuity and reduce "noise."
2.) Ciliary muscle: Mediates lens accommodation
L8a #21
113
1. ) What type of muscle is the ciliary body?
2. ) What is its innervation?
3. ) It exists at the border of the ________ and ______.
1.) Circular smooth muscle for accommodation.
2.) PSNS innervation by Edinger-Westphal nucleus (CN III)
3.) Exists at the border of aqueous and vitreous humor.
L8a #21
114
1. ) What intraocular pressure constitutes glaucoma?
| 2. ) What two general problems can cause glaucoma?
1. ) > 22mmHg
| 2. ) Increased production of aqueous fluid, decreased purging by canals of Schlemm
115
1.) Describe open vs closed angle (include what the "angle" is) glaucoma and which is more prevalent. What type of deformation is NOT manifested through glaucoma?
1. ) The "angle" is between iris and cornea, with the vertex being the trabecular meshwork
a. ) Open angle (> 90%): Slow clogging. Aqueous humor slowly builds up in the anterior chamber (i.e. travel back to the posterior chamber is slowed), pushing the iris and lens back towards the vitreous chamber and retina. Angle between iris and cornea is "open".
b. ) Closed angle (less than 9%): Sudden blockage. Aqueous humor cannot drain. As a result, The angle of the anterior chamber becomes "closed" (i.e. the iris is pushed towards the cornea) and there is back pressure on the lens.
*There is NO CORNEAL DEFORMATION as a result of the increased pressure in either case*
2.) Both cases lead to supply/circulation problems in the back of the eye (damages BVs and induces neural degeneration), thus *compromising retinal vitality.*
L8a #23
116
What structure delineates the anterior and posterior portions of the aqueous chamber?
Iris
| L8a #24
117
1. ) What is a common component of anterior surface and stroma of the iris?
2. ) Describe the two portions of the posterior surface of the iris
1. ) Fibroblasts (stellate on the anterior fenestrated surface).
2. ) Inner/posterior epithelium = PIGMENTED. Outer layer contains the DILATOR pupillae.
118
Where are the two pupillary muscles found, what type of muscles are they, and what type of innervation does each receive?
1.) Dilator pupillae: Radial smooth muscle in the outer layer of the posterior surface of the iris. SNS innervation via superior cervical ganglion.
2.) Sphincter pupillae: Constricting circular smooth muscle sphincter around the pupillary margin. PSNS innervation via pterygopalatine ganglion.
L8a #25
119
Where are melanocytes found in the iris and what is their purpose?
Within the stroma; they prevent distortion of image formation by scattered light.
L8a #25
120
Describe the three lens components. How is it held in place?
1.) Capsule: Thick BM; consists mainly of type IV collagen.
2,) Subcapsular epithelium: Only on anterior surface of lens.
3.) Lens fibers: Elongated and appear as thin, flattened structures. Filled with proteins called "Crystalins" (disorganization of crystallins contributes to lens opacity, i.e. CATARACTS).
*Lens held in place by radial ZONULE fibers (critical for accommodation).
L8a #27-28
121
Describe accommodation in terms of innervation, focus, muscle action, choroid-lens relation, zonule fibers, lens shape, and affect on light rays.
Innervation: PSNS via Edinger-Westphal nucleus.
-Focus on close objects.
-Ciliary muscles contracts and pulls posterior border of choroid towards the lens.
-Zonule fibers relax, causing the lens to thicken and become more round in shape.
-Round lens shape causes greater convergence of light rays (light bends more) within the eye globe.
L8a #29
122
Describe distance focus within the same parameters as accommodation
-Ciliary muscles relax (choroid moves away from lens), zonule fibers tighten and the lens flattens.
-Flat lens = Less convergence of light rays = longer focal point.
L8a #30
123
Describe the cause and symptoms of the following:
1. ) Cataracts
2. ) Presbyopia (akin to _______)
1.) Opacity of the lens caused by disorganization of *crystallins (protein) and collagen* within the lens fibers, i.e. change in solubility of the lens proteins.
2.) Reduced elasticity of the lens with aging that causes impaired accommodation. As a result, focusing on close object becomes difficult. In other words, LENS LOSES THE ABILITY TO MAINTAIN A ROUND SHAPE. This is akin to HYPEROPIA (far vision).
L8a #31
124
What are the four functions of pigmented retinal epithelium?
1.) *Esterification of Vitamin A*
2.) Blood-retina barrier: Junctional complexes between adjacent retinal pigmented epithelial cells prevents blood from choroid from getting into the neural retina.
3.) *Melanin synthesis* (collects errant light)
4.) Phagocytosis of shed tips from rods and cones.
L8a #34
125
What is a rhegamogenous retinal detachment?
Occurs due to a break in the retina (retinal tear) that allows fluid to pass from the vitreous space into the subretinal space (between retina and sclera), further detaching the two layers and removing blood supply from retina.
L8a #36
126
1. ) Axons of retinal ganglion cells gain myelin after _________.
2. ) ______ is contiguous with the epineurium of the optic nerve at this point.
3. ) This general area also serves at the entry point for what structure?
1.) After they exit the neural retina and form the optic nerve (cannot happen within the eye globe because myelin reflects light).
2.) Sclera
3.) Central artery of the retina (from ophthalmic artery).
L8a #62
127
1. ) What type of vision is lost in patients with retinitis pigmentosa and why?
2. ) What isn't affected by retinitis pigmentosa?
1.) Loss of parafoveal and peripheral vision because of lost rods/rhodopsin = Tunnel vision, lack of night vision, bad at detecting motion, etc.
2.) No appreciable affect on optimal *visual acuity.*
L8a #66-67
128
1. ) Lateral processing retains separation of _________.
2. ) Lateral processing produces inhibitory or excitatory effects _______, however, AP potentials only occur in the ________.
1.) Rod and cone processing.
2.) Post-synaptically, ganglion cell layer.
L8b #8
129
From which retinal and visual fields does the lateral geniculate body receive projections (2), and where do the fibers terminate?
1. ) Fibers from the IPSILATERAL TEMPORAL hemiretina (nasal hemifield) – which terminate in layers 2, 3, and 5 of the LGN.
2. ) Fibers from the CONTRALATERAL NASAL hemiretina (temporal hemifield) – which terminates in layers 1, 4, and 6 of the LGN.
p. 224 BRS
130
1. ) Photoreceptors have _______, ________ receptive fields.
| 2. ) Receptive field size ______ with downstream cells due to _________.
1.) Very *narrow, homogenous* receptive fields.
2.) Enlarges (increases in size AND complexity) with downstream cells due to radial and horizontal circuitry.
L8b #11
131
Meyer's loop projects to the _____ bank of the calcarine sulcus, and thus, carries information from the _______ retinal quadrant ( _____ quadrant of the visual field).
Inferior bank, inferior retinal quadrant, superior quadrant of the visual field.
Look at Netter picture p.84
132
What is the arc (in degrees) of the binocular visual field? Monocular?
-Binocular: 120˚ of *total* visual field (central and paracentral).
-Monocular: 30˚ of L and R visual fields (peripheral vision).
L8b #32
133
What does the Snellen test evaluate for (2)?
High contrast detection and photopic vision.
| L8b #38
134
How does the LGN receptive field and firing rate differ from that of the retina? Similarities?
Like the retina, LGN has a round, antagonistic center-surround visual field. However, the firing response of the LGN has more emphasis on *CONTRAST*, though with similar firing *patterns* (more dense/higher frequency during firing, and more down time during rest).
*Really only makes sense when seen with image*
L8b #45
135
1. ) What does the organ of Corti contain (2)?
| 2. ) What is it supported by (i.e. what does it rest on)?
1. ) Hair cells and tectorial membrane
2. ) Basilar membrane
p. 203 BRS
136
What keeps the endolymph separate from the perilymph?
Tight junctions among hair cells
| L9a #18
137
What forms the roof over the organ of Corti?
Tectorial membrane
| L9a #19
138
What two things support auditory hair cells?
Rod cells and columnar cells
| L9a #21
139
Concerning the basal membrane, low frequencies generate waves that distort the ______ end of the membrane.
```
Apical end (i.e. apex)
L9a #23
```
140
1st order fibers in cochlear nerve terminate in the ________. Where is this (i.e. location within structures of the CNS)?
Cochlear nuclei —> Lateral upper medulla (ponto-medullary junction), but also exists in the caudal pons. Dorsal and ventral nuclei – proximal to *INFERIOR CEREBELLAR PEDUNCLE*
L9a #46
141
1. ) Where do you place an auditory implant in patients who lost their auditory nerve? Why here (2)?
2. ) Who are candidates? What is a typical cause of their hearing loss?
3. ) Compare to cochlear implantation
1.) Directly in cochlear nuclei (direct stimulation of cochlear nuclei) – Bypass cochlea and auditory/cochlear nerve. Neural implants placed here because this location has the *richest innervation from inner hair cells* (as opposed to the superior olivary nucleus).
2.) > 15 years old with history of hearing loss – common cause is *neurofibromatosis Type 2*
3.) Not as good – speech identification is weaker.
L9a #47
142
1. ) Where is the trapezoid body?
| 2. ) What two structures meet there?
1.) At the base of the pontine tegmentum (next to the base of the pons) —> i.e. Dorsal caudal pons .
2.) Intermediate and anterior acoustic striae
L9a #57
143
What are the four auditory processing cortices (give area and function)?
1.) 1˚ auditory cortex (41-42; Herschl's gyri)
2.) Superior temporal gyrus (22) – Generation and understanding of words.
3.) Parietal cortex (39 and 40; Wernicke's area) – Receptive speech
4.) Frontal cortex (44 and 45; Broca's area) – Expressive speech.
L9a #60
144
Tonotopic organization of tones is established in the _______ and reflected richly in the _________.
-Established in the periphery
-Reflected richly in the cochlear nuclei
L9a #62
145
Describe tonotopic organization in Heschl's gyri
-Lower frequency on BODY of gyri
-Higher frequency in SURROUNDING area
L9a #64
146
Vestibulation communicates with other senses that help you do what?
Place you in space and assess the dynamics of your changing position *with time*
L9b #5
147
The receptor apparati for vestibulation are found where?
Embedded in petrous bone
| L9b #6
148
The vestibular system exerts its effects over which bodily functions/systems (2)? How? Examples (2)?
Musculature and viscera through descending projections to spinal cord, e.g. ANS and skeletal muscles (particularly of head and neck).
L9b #7
149
1. ) The utricle is maximally stimulated when the head is bent...(3)
2. ) The saccule is maximally stimulated when the head is bent...(3)
1.) forward or backward or side to side.
2.) forward or backward or up-and-down.
BRS p.212
150
Only semicircular canals oriented in _______ will respond to angular acceleration.
Oriented in the plane of movement.
| L9b #10
151
Compare the orientation of hair cells in the otolith organs vs those in the organ of Corti
Otolith: Arranged in a cone-like shape so that they may respond to a wider range of motion in their plane.
*Some hair cells are maximally excited, some inhibited, and others unaffected by a particular movement*
Corti: Linear; do not need to move throughout a wide range.
L9b #12
152
What does the Barany chair test for (2)?
1˚ vestibular responses: (Dis)orientation and balance
2˚ vestibular responses: Vomiting and nausea
L9b #38
153
1. ) What do the olfactory bipolar neurons lack in their cilia that renders them non-motile and specialized for olfaction?
2. ) What is another term used for these cilia?
1.) They lack DYNEIN that is present in normal cilia.
2.) Olfactory hair
L9c #10-11
154
Trace the progression of the olfactory axon into the olfactory tract
Unmyelinated axon —> Olfactory fila —> Olfactory nerve (through cribiform plate) —> Olfactory bulb —> Olfactory tract (in a glomerulus) *Each axon synapses with ONE glomerulus.
L9b #10-11
155
What are the layers of olfactory bulb from outside in (8), and which cell/structures are in each layer? Indicate excitatory or inhibitory action for each. *Include axons, dendrites, epi, etc.*
1.) Olfactory epithelium: Olfactory receptor neurons (1st order)
2.) Cribiform plate
3.) Olfactory nerve layer: Bipolar neuron axons
4.) Glomerular layer: Olfactory glomerulus, dendrites and bodies of periglomerular cells (–), centrifugal afferent fibers (+), receptor neuron axons (+), mitral cell dendrites (+), tufted cell dendrites (+).
5.) Outer plexiform layer: Tufted cell bodies and dendrites (+), granule cell dendrites (–).
6.) Mitral cell layer: Mitral cell bodies and dendrites (+), granule cell dendrites, centrifugal fibers (+).
7.) Granule cell layer: Granule cell bodies and dendrites (–), dendrites of every other cell except periglomerular.
*Olfactory tract begins at this point*
L9c #18
156
What type of pathology is likely to cause phantosmia?
Lesion in cortical efferents
| L9c #32
157
How are the taste regions divided in the tongue?
They are NOT. All the taste qualities are detected in all regions of the tongue.
L9c #36
158
How are taste buds stimulated?
Tastant binds microvilli (with receptors),
