Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Year 2: NeuroBiology > Lecture 7: CNs and Special Sensation > Flashcards

Lecture 7: CNs and Special Sensation Flashcards

1
Q

Number/type of neurons involved with olfaction/CN I and how often they renew

A

approximately 3 million bipolar neurons

they renew every 30-60 days by stem cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how do signals for the olfactory n travel

A

axons of olfactory receptor neurons in sphenoethmoid recess of nasal cavity

dendrites have multiple cilia at the ends of neurons

odorant receptor = defines chemical identity

odorant binding protein = facilitates odors to cross mucus surface

CN V fibers are spread throughout the sheath of the olfactory epithelia and can detect pungency too

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What defines a smell’s chemical identity

A

Odor receptors

mainly GPCR

some ionotropic receptors but less

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

speed/myelination of olfactory n

A

nonmyelinated

thinnest axons (0.2 micro m)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is an olfactory fila

A

20-30 axons bundled together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

where does the olfactory n cross/synapse

A

cribiform plate

synapse with olfactory bulb in CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

describe the olfactory bulb (where, what it does)

A

component of telencephalon

specific synapse with mitral cell dendrite (glomeruli are odorant specific functional unit)

sort signals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how does signal sorting work at the olfactory bulb

A

olfactory receptor protein defines odor specificity

axons of olfactory receptor neurons for the same odor run together

mitral cells of same odor synapse with pyramidal cells in neocortex (olfactory cortex)

glutamate and carnosine as excitatory neurotransmitters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are centrifugal fibers important for

A

negative circuit regulating odorant detection

adapting to odors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

where are the 1st-3rd order neurons of the olfactory path

A

1st = olfactory receptor neuron

2nd = mitral cell

3rd = only for sensation; doesn’t need thalamic relay for conscious perception

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

describe the path of olfactory projection

A
  1. anterior olfactory nucleus in olfactory tract
  2. cross at anterior commisure
  3. olfactory tubercle
  4. piriform cortex (uncus, limbic lobe)
  5. amygdala (emotional learning, aversion)
  6. periamygdaloid cortex
  7. anterior portion of parahippocampal gyrus (entorhinal cortex specifically: memory)
  8. primary olfactory cortex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

indirect projections from the primary olfactory cortex (piriform cortex and periamygdaloid)

A

hypothalamus: drive

amygdala: emotional learning

hippocampus: memory

thalamus: relay station and coordination (goes to
olfactory association cortex in insula near the gustatory cortex; gives perception of flavor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

4th week landmark of eye development

A

protrusion of optic vesicle from diencephalon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

5th week landmarks of eye development

A

optic vesicle folds in to form double layered optic cup

invasion of ectoderm forms lens vesicle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

6th week landmarks of eye development

A

optic cup inner later: retina

optic cup external layer: retinal pigment epithelia

both layers: continue to grow anteriorly to form ciliary body and iris

lens vesicle: pinch off to form lens

leftover ectoderm: forms cornea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the 2 anatomic landmarks around the eye

A

ora serrata: anterior end of photosensitive retina

limbus: circular transition zone, junction of cornea and sclera

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

structures in internal and external layers of the eye

A

sclera and cornea (junction = limbus)

choroid capillaries: provides blood supply and obsorbs stray light

retina and cilliary body (end forms ora serrata)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

special structures found in the eye

A

ciliary body = lens accomodation and aqueous humor secretion

iris = adjusts to allow light to pass through

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the aqueous humor

A

anterior to the lens

secreted by epithelias in ciliary body

drains into scleral venous sinus and then to venois drainage of the eye

increases inner pressure to maintain eyeball shape along with vitreous humor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is glaucoma

A

increased production or blocked circulation of aqueous humor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is vitreous humor

A

glass like humor in eyeball

posterior to lens

increases inner pressure to maintain eyeball shape along with aqueous humor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

how does the eye “focus” on something

A

refraction of light by the transparent cornea and lens

cornea = conves anteriorly; maintained through intraocular pressure; light passes through with most refraction - gross adjustment

lens = biconvex; but only anterior portion can be adjusted - fine adjustment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

how does the lens adjust for near vs far sight

A

ciliary muscle contraction = zonular fibers loosen; for NEAR sight

ciliary muscle relaxation = zonular fibers tighten; for FAR sight

controlled by parasympathetic motor from CN III

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is a cataract

A

degeneration of lens that results in blindness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what components are involved with adjustment of brightness and image quality of the eye

A

iris: pinhole effects- pupil dilation/constriction

retina: major role in visual sensitivity adjustment; absorbs stray light by pigmented epithelia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

describe how the “pinhole effect” works with pupil dilation/constriction

A

pupillary sphincter/constrictor pupillae (controlled by CN III)
- m is circular, developed from edge of optic cup
- decreases iris diameter to allow less light into eye

pupillary dilatro/dilator pupillae (sympathetic motor)
- radiating spokes
- increases diameter of iris to allow more light into eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

how many layers in human retina

A

10

opposite to direction of light and information processing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

describe the layers/cells of the retina from outer to inner side

A

outer synaptic layer = 5 cells
- rods and cones: photoreceptors
- bipolar neurons: converge info from photo receptors

inner synaptic layer = 2 cells (interneuron and ganglion)
- axonal bundles of ganglion cells form optic n coursing through optic canal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

describe the blind spot of the retina

A

optic disk = no photoreceptors

cant feel it but can be proved; lose huge visual field without being aware

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

describe the macula portion of the retina

A

circular portion

lateral to optic disk

2mm diameter

yellowish in color due to numerous blue light absorbing cells (macula lutea)

fovea = center of macula; 0.35 mm diameter, concentrated cones, high visual acuity

peripheral retina: more rods for black and white

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what is macular degeneration

A

lost visual acuity

legally blind

32
Q

what is a bipolar cell and the different types

A

NOT a neuron; no initiation of AP

“on” bipolar cell = active in light; inhibit glutamate production; metabotropic receptor

“off” bipolar cell = inactive in light; activate glutamate production; ionotropic receptor

1st order neuron to converge signals from photon receptors

33
Q

describe a ganglion/its role in the visual system

A

2nd order neuron

over 20 types in humans

further converge signals from bipolar cells

34
Q

X/P/beta ganglion cell functions with vision

A

color and finer details

convergence from cones

35
Q

Y/M/alpha ganglion cell functions with vision

A

motion and course patterns

convergence from rods

36
Q

purpose of melanopsin containing ganglion cells

A

sensitive to light intrinsically; no convergence from bipolars

W/K type for circadian rhythm

pupillary light reflex still exists in blind people with injured photoreceptors

37
Q

what cells modulate the transmission pathway of the visual system

A

horizontal and amacrine cells

38
Q

describe the projection of the optic tract

A

ganglion axons project to lateral genticulate nuclei of thalamus (3rd order neuron)

relayed info goes to V1 (primary visual cortex)

39
Q

what information is received/interrpreted at the primary visual cortex

A

only directional bars detected

macula projects to posterior/occipital part; takes over 60% of V1

Meyer’s loop: inferior projection fibers course through the temporal lobe; superior quadrant of V1

contralateral visual field is detected by visual cortex, NOT visual field of each eye

40
Q

where does the dorsal stream projections from the primary visual cortex project to? and what information does it carry?

A

via Y/M/alpha ganglia

to parietal lobe: where (location/shape/motion/speed of objects); R side dominant

to medial temporal lobe: navigation

to frontal lobe: how

41
Q

where does the ventral stream projections from the primary visual cortex project to? and what information does it carry?

A

X/P/beta ganglia

to the inferior temporal lobe: what
- retrieve memory about name of objects
- continue to project to medial temporal lobe

42
Q

what kind of info does V1 provide in visual perception

A

lines with different directions

maintains retinotopy

43
Q

what kind of info does V4 provide in visual perception

A

different colors

retinotopy maintained

44
Q

integration of the visual cortex and the dorsal/ventral streams allows us to maintain what

A

object shape/color

perception
- name/correlated info
- spatial location
- action

45
Q

describe how a visual field works

A

both eyes have right and left visual field with central region overlapping

46
Q

nasal vs temporal retina

A

nasal is side of retina toward nose

temporal is side of retina towards temple

47
Q

how does cross projection of the visual field to the retina work

A

L visual hemifield by right temporal and left nasal retina (“right side of each eye”)

R visual field by L temporal and R nasal retina (“left side of each eye”)

48
Q

what forms the optic chiasm

A

contralateral nasal retina axons cross to form optic chiasm

49
Q

what forms optic tract

A

axons from temporal retina and contralateral nasal retina

L optic tract for R visual field and R optic tract for L visual field

50
Q

what pathology should be screened when a pt presents with tunnel vision

A

pituitary gland tumor impinging optic chiasm

51
Q

what is L homonymous hemianopia

A

lost visual field of one side entirely

52
Q

what is blindsight/Riddoch’s phenomena

A

V1 lost function entirely still with vision of motion

53
Q

what happens with parallel processing at tectopulvinar pathway

A

pretectal area and superior colliculus coordinate eye movement

pupillary light reflex

visual association area via dorsal stream

54
Q

importance of projection of optic tract to hypothalamus

A

suprachiasmatic nuclei

relay info for circadian rhythm

55
Q

what are the locations that CNs III, IV, and VI cross the meninges and cranium

A

meninges = different

cranium = superior orbital fissure
- sphenoid bone has multiple CN crossing openings

56
Q

what does levator palpebrae muscle control and what is its innervation

A

CN III

common tendinous ring in the posterior orbital wall

controls upper eyelid and opens the eye

57
Q

extraocular muscles innervated by CN III

A

superior rectus

medial rectus

inferior rectus

inferior oblique (maxilla)

58
Q

extraocular muscles innervated by CN VI

A

lateral rectus

59
Q

extra occular muscles innervated by CN IV

A

superior oblique

60
Q

what is convergence

A

adduction of bilateral eyeballs at the same time focusing on same targe (near triads)

61
Q

what is pathological strabismus

A

2 eyes not lined up properly to different directions

62
Q

esotropia

A

adducted eyeball(s)

convergence (functional)

CN VI palsy

63
Q

exotropia

A

abducted eyeball(s)

divergence

medial rectus strain

CN III palsy

64
Q

hypertropia

A

elevated eyeballs

CN IV palsy (superior oblique)

65
Q

hypotropia

A

depressed eyeballs

inferior oblique muscle strain

CN III palsy

66
Q

describe the path for visceral motor function via CN III `

A

preganglionic axons from Edinger Westphal nuclei (EW)

synapse with 2nd cell body in ciliary ganglion

post ganglionic axons hike on short ciliary n

67
Q

ciliary body function

A

regulate lens convexity

68
Q

pupillary sphincter function

A

constrict iris

69
Q

where does efferent and afferent info come from in relation to pupillary light reflex

A

afferent = optic n; ganglionic cells; no photoreceptor needed

efferent = oculomotor n, Vm

effects = constrict pupil

70
Q

where are the nuclei for the trigeminal n

A

in whole brainstem and upper cervical spinal cord

3 ss nuclei

1 sm nucleus

71
Q

where is CN V located

A

middle and lateral pons

72
Q

CN V crosses the dura and then each branch crosses at different cranial foramina. what are the foramina for each branch

A

V1, opthalmic n, ss only: superior orbital fissure

V2, maxillary, ss only: foramen rotundum

V3, mandibular, ss and sm: foramen ovale

73
Q

somatosensory functions of CN V

A

facial sensory stimuli

chemical sensation of taste and smell

74
Q

somatic motor functions of CN V

A

mastication (temporalis, masseter, medial and lateral pterygoids)

tensor tympani: hearing

tensor veli palatini: swallowing

digastric anterior belly and mylohyoid: speaking/swallowing

75
Q

how does CN V act as a shuttle for other CNs

A

CN III and sympathetic post ganglionic axon: short ciliary n

CN VII
- zygomatic n to lachrymal n: postganglionic axon to lacrimal glands

  • lingual n: chorda tympani for taste and parasympathetic components

CN IX: auriculotemporal n for postganglionic axon to parotid gland

76
Q
A

Year 2: NeuroBiology (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions