CNS Physiology Flashcards
(180 cards)
1
Q
tau fx
A
binds and stabilizes microtubules
problems –> neurofibrillary tangles (NFTs)
e.g. AD
2
Q
astrocytes
A
bbb
regulate extraneuronal ion conc
remove nt’s
form scars in response to injury (can be good or bad)
3
Q
oligodendricytes
A
form myelin in CNS
1 cell –> up to 10 axons
4
Q
microglia
A
macrophage-like
5
Q
gray matter
A
cell bodies
e. g.
- cortex (surrounds brain or cerebellum)
- nucleus (cluster of gray matter within brain, i.e. surrounded by white matter)
- ganglion
- horn (spinal cord)
6
Q
white matter
A
fibers/axons
e. g.
- nerve (PNS)
- tract (CNS)
- – named “from-to” e.g. corticospinal = from cortex (brain) to spinal cord
- fasciculus
- lemniscus
- column
- capsule
- commissure
- peduncle
7
Q
pain receptors in meninges
A
in dura mater only
8
Q
ependymal cells
A
line the ventricles make CSF (most specifically choroid epithelial cells do, which are a specialized form of ependymal cell)
9
Q
nissl substance
A
ribosomes and rER of neuron
stains blue with nissl stain
10
Q
ventricular system and embryologic origin
A
makes CSF
from vesicles in neural tube
CSF flows from:
- lateral ventricles to
- third ventricle to
- cerebral aqueduct to
- fourth ventricle to
- subarachnoid space (especially large cisterns; no longer part of ventricular system)
11
Q
lateral ventricles supply
A
forebrain (telencephalon)
12
Q
third ventricle supplies
A
forebrain (diencephalon)
13
Q
cerebral aqueduct supplies
A
midbrain (mesencephalon)
14
Q
fourth ventricle supplies
A
hindbrain (rhombencephalon)
- cerebellum, pons, medulla
15
Q
most specifically, what makes CSF and (roughly) how?
A
choroid epithelial cells
- specialized ependymal cells
- make up choroid plexus
- line ventricles
- most abundant in lateral ventricles
filters blood, adds extra ions
16
Q
foramen of monro
A
connects lateral to third ventricle (allows CSF flow)
17
Q
exit point of CSF from ventricular system
A
afer 4th ventricle
- 1x foramen of magendie (medial)
- 2x foramen of luschka (lateral)
18
Q
cisterns
A
large spaces of subarachnoid space collect CSF (passively) upon exit from ventricular system
19
Q
flow of CSF once out of ventricular system
A
- subarachnoid space to
- superior sagittal sinus
- – reabsorbed by arachnoid villi, clustered in arachnoid granulations
20
Q
arachnoid villi
A
reabsorb CSF
in superior sagittal sinus
cluster in arachnoid granulations
21
Q
if decussation occurs, it’s at level of ____ order neuron
A
second order neuron (cell body)
22
Q
afferent fiber types by size and conduction velocity
A
biggest = fastest
- A-alpha (largest)
- A-beta
- A-delta
- C (smallest, unmyelinated)
23
Q
the ____(biggest/smallest) afferents are involved in balance
A
biggest
24
Q
A-alpha fibers
A
biggest, fastest
balance
primary muscle spindles
Golgi tendon
25
A-beta fibers
skin mechanoreceptors
| secondary muscle spindles
26
A-delta fibers
coarse touch
temperature
sharp pain
27
C fibers
smallest, slowest
unmyelinated
affective touch
aching pain
28
location of afferent n. cell bodies
dorsal root ganglia
29
afferent n. enter at ___ horn
dorsal
30
gracile tract
carries afferents from below T6 (lower limbs and body)
more medial in spinal cord
DC-ML pathway
31
cuneate tract
carries afferents from above T6 (upper limbs and body)
more lateral in spinal cord
DC-ML pathway
32
first synapse gracile tract fibers
gracile nucleus
33
first synapse cuneate tract fibers
cuneate nucleus
34
second order DC-ML afferent n. form ___
internal arcuate fibers of caudal medulla
| decussates to medial lemniscus
35
second order DC-ML afferent n. terminate in
ventral posterior lateral (VPL) nucleus of thalamus
36
VPL neurons project to
primary somatic sensory cortex
| via posterior limb of internal capsule
37
lassauer's tract
carries first order sensory discriminative afferents
| key component of central pain pathways
38
spinothalamic tract
carries second order sensory discriminative afferents
| central pain pathway
39
spinothalamic tract n. terminate in
VPL of thalamus
40
DC-ML pathway senses ___
light touch
vibration
2 point discrimination
position
41
spinothalamic pathway senses
pain
temperature
coarse touch
42
periacqueductal gray
one of key regions in affective-motivational component of pain (i.e. descending control)
43
Golgi tendon organ
lie between group of muscle fibers and tendon
| sense muscle tension
44
autogenic inhibition
negative feedback loop to control muscle tension
45
corticospinal tract
~85% of descending motor control
location in spinal cord:
- lateral
fx:
- isolated, skilled movement of digits
- voluntary, goal-directed, skilled movement
pathway:
- cell body: primary motor cortex
- thru posterior limb of internal capsule
- cerebral peduncles
- to corticospinal and corticobulbar tracts
- thru pyramids of medulla
* pyramidal decussation
- crossed fibers --> lateral corticospinal tract, others to anterior
46
rubrospinal tract
location in spinal cord:
- lateral
- adjacent to corticospinal tract
fx:
- flexor and distal muscle of upper limbs
pathway:
- cell bodies: red nucleus (midbrain)
- immediate decussation
47
reticulospinal and vestibulospinal tract
location in spinal cord:
- medial
fx:
- extensor muscles
- automatic control of posture and balance
- proximal/axial musculature
48
decussation of corticospinal tract
pyramids of medulla
49
in corticospinal tract legs are more ___ (position in spinal cord) and arms are more ___
```
legs = lateral
arms = more medial
```
50
decussation of rubrospinal tract
immediate (red nucleus, midbrain)
51
location of CN nuclei
brainstem
52
CN III fx
oculomotor:
- superior rectus (up)
- inferior rectus (down)
- medial rectus (aDduction/medial)
- inferior oblique (extortion)
- levator palpeerde superioris (raise eyelid)
Edinger-Westphal nucleus:
- pupil constriction
- lens accommodation
* ipsilateral
- L lesion affects L eye
53
CN III origin
oculomotor nucleus
| rostral midbrain
54
pupillary light reflex
light in one eye --> constriction in both eyes
55
CN IV fx
superior oblique
56
CN IV origin
caudal midbrain
immediate decussation
exits dorsally
57
CN VI fx
lateral rectus (aBduction)
58
CN VI origin
caudal pons
| aBducens nuclei
59
CN V fx, nuclei
fine touch and proprioception from face
- sensory nucleus/main nucleus
pain, temperature, coarse touch from face
- spinal nucleus of trigeminal complex
mastication, middle ear muscle (tensor tympani)
60
CN V divisions
V1: opthalmic
V2: maxillary
V3: mandibular
61
CN VII fx, nuclei (there are 3)
taste (anterior 2/3 of tongue)
- nucleus of solitary tract
facial expression
- facial nucleus
salivary and other glands/membranes
- superior salivary nucleus
62
CN IX fx, nucleus
- glossopharyngeal
* carotid body
- sensory from oral and nasal cavities
- taste from posterior 1/3 of tongue
- motor control of stylopharyngeus
- -- nucleus ambiguus
63
CN X fx, nuclei (there are 3)
autonomic motor
- dorsal motor nucleus of vagus
- incl most muscles of palate, pharynx, and larynx
- -- this is from nucleus ambiguus
visceral sensory
- nucleus of solitary tract
- incl taste from epiglottis and larynx
- incl chemo- and pressure receptors from aortic arch
64
CN XI fx, nucleus
motor control of SCM and trapezius
- LMNs in ventral horn of spinal cord
- origin in (very) caudal medulla
65
CN XII fx, nucleus
- intrinsic muscles of tongue
| - Hypoglossal nucleus
66
gracile nucleus
- tactile from lower half of body
location
- caudal medulla (closed)
67
cuneate nucleus
- tactile from upper half of body
location
- caudal medulla (closed)
68
medial lemiscus
- tactile from gracile and cuneate nuclei (whole body)
- contralateral
location
- caudal medulla (closed)
- rostral medulla (open)
- caudal pons
- rostral pons
- caudal midbrain
- rostral midbrain
69
anterolateral tract
- pain from body
location
- caudal medulla (closed)
- rostral medulla (open)
- caudal pons
- rostral pons
- caudal midbrain
- rostral midbrain
70
spinal nucleus of trigeminal
pain from face
location
- caudal medulla (closed)
- rostral medulla (open)
- caudal pons
71
nucleus ambiguus
- motor neurons of pharynx and larynx
- shared b/w CN IX and X
location
- caudal medulla (closed)
72
corticospinal tract
motor information to body
location
- caudal medulla (closed)
73
rostral nucleus of solitary tract
- taste
- shared among CN VII, IX, and X
location
- caudal medulla (closed)
- rostral medulla (open)
74
caudal nucleus of solitary tract
- visceral receptors for cardio and respiratory reflexes
- shared CN IX (carotid body) and X (aortic arch)
location
- caudal medulla (closed)
- rostral medulla (open)
75
dorsal motor nucleus of vagus
- thoracic and abdominal viscera
- para pre
location
- caudal medulla (closed)
- rostral medulla (open)
76
hypoglossal nucleus
motor neurons of tongue
location
- caudal medulla (closed)
- rostral medulla (open)
77
medial longitudinal fasiculus (MLF)
- oculomotor connections
- tectospinal and medial vestibulospinal tracts
- CN XI
location
- caudal medulla (closed)
- rostral medulla (open)
- caudal pons
- rostral pons
- caudal midbrain
- rostral midbrain
78
vestibular nuclei
proprioception
- linear and angular acceleration info from CN XIII
location
- rostral medulla (open)
- caudal pons
79
inferior cerebellar peduncle
- input to cerebellum
- from posterior spinocerebellar tract and medulla
- some output to medulla
location
- rostral medulla (open)
80
inferior olivary nucleus
- input to cerebellum
location
- rostral medulla (open)
81
cochlear nuclei
- auditory info from CN VIII
location
- rostral medulla (open)
82
sensory nucleus of trigeminal
tactile from face
CN V
location
- caudal pons
83
motor nucleus of trigeminal
motor neurons for mastication
location
- caudal pons
84
middle cerebellar peduncle
- main input to cerebellum
- from pontine nuclei
location
- caudal pons
85
pontine nuclei
- input from ipsilateral corticopontine fibers
- to contralateral cerebella via pontocerebellar fibers
location
- caudal pons
- rostral pons
- caudal midbrain
86
corticobulbar fibers
- motor information to medulla
location
- caudal pons
- rostral pons
87
corticospinal fibers
- motor info to body
location
- caudal pons
- rostral pons
88
aBducens nucleus
- motor to lateral rectus (CN VI)
location
- caudal pons
89
facial nucleus
motor to face (CN VII)
location
- caudal pons
90
superior olivary nucleus
first step of auditory processing from cochlear nucleus
location
- caudal pons
91
superior cerebellar peduncle
- main output from cerebellum
- to thalamus and red nucleus
location
- rostral pons
- caudal midbrain (decussation)
- rostral midbrain
92
lateral lemniscus
- auditory info from cochlear and superior olivary nuclei
location
- rostral pons
- caudal midbrain
93
decussation of trochlear nerve
Immediate
motor to superior oblique (crossing over point)
location
- rostral pons
94
inferior colliculus
- second step of auditory processing
- from lateral lemniscus
location
- caudal midbrain
95
cerebral peduncle (what fibers/tracts)
- corticopontine, corticobulbar, and corticospinal fibers
location
- caudal midbrain
- rostral midbrain
96
periaqueductal gray
- descending control of pain
- etc.
location
- caudal midbrain
- rostral midbrain
97
trochlear nucleus
motor to superior oblique (CN IV)
location
- caudal midbrain
98
decussation of superior cerebellar peduncle
Level of inferior colliculi
- crossing over of main output of cerebellum
- to thalamus and red nucleus
location
- caudal midbrain
99
superior colliculus
- shift of gaze (head and eyes)
- attention
location
- rostral midbrain
100
brachium of inferior colliculus to and from
- auditory from inferior colliculus
- to medial geniculate nucleus
location
- rostral midbrain
101
substantia nigra and its parts
- part of basal ganglia
- compact part: dopaminergic neurons to striatum
- reticular part: from striatum to thalamus
- damaged in PD
location
- rostral midbrain
102
edinger-westphal nucleus
para pre neurons for pupil constriction
location
- rostral midbrain
103
oculomotor nucleus
motor to superior rectus, inferior rectus, medial rectus, inferior oblique (CN III)
location
- rostral midbrain
104
red nucleus
- motor control via inferior olivary nucleus and rubrospinal tract
location
- rostral midbrain
105
ventral tegmental area
- reward and reinforcement of behavior
location
- rostral midbrain
106
mechanisms of regulation of regional cerebral blood flow (rCBF)
1. metabolic coupling
- need for O2 and glucose (metabolic demand) increases volume of blood flow
2. PaCO2
- increase --> vasodilation
3. cerebral perfusion pressure
- differential to MAP
- autoregulated to maintain a more consistent pressure vs MAP, between ~70 and 140 MAP
4. neural control
- intrinsic and extrinsic
107
components of BBB
- endothelial cells w/ tight junctions
- basal lamina = ECM connecting endothelial cells to astrocytes
- astrocytic end feet: biochemical support to endothelial cells
- pericytes: wrap around endothelial cells, structural support and vasodynamic capacity to microvasculature
108
mx of BBB regulation
- enzymes on cell surface inactivate many drugs
- tight junctions restrict paracellular diffusion
- located at both endothelial cells and epithelial cell surface of choroid plexus
109
immune recruitment to CNS
- immune cells have components that can break down BBB
- paracellular and transcellular
- shown in many neuro disorders incl MS, stroke
110
reticular formation
- not a nucleus or tract
- central core of brainstem from midbrain to medulla
- heterogenous cluster of neurons make net-like (reticular) appearance
- neurons can have long-range projections thru brain and spinal cord
fx:
- modulate excitability of distant neurons
- arousal and consciousness
- pain pathways
- gaze control
- respiration
- sneezing
- swallowing (includes nucleus ambiguus)
- control of movement - connections w/ spinal cord and cerebellum
111
serotonergic system
fx:
- depending control of pain
- sleep-wake
- affect
nuclei:
- raphe nuclei in brainstem
112
noradrenergic system
fx:
- attention and vigilance
- sleep-wake
nuclei:
- locus ceruleus
- reticular formation
- both in brainstem
113
dopaminergic system
fx:
- initiation and speed of movement
- motivation, reward, reinforcement
nuclei:
- substantia nigra
- ventral tegmental area
- both in midbrain
114
reticular activating system
fx:
- maintaining consciousness (bilateral lesions --> coma)
nuclei:
- midbrain and rostral pontine tegmentum
115
general cerebellar pathway
- input >
- thru cerebellar penduncle
- cerebellar cortex
- cerebellar nuclei
- back thru cerebellar peduncles
- > output
feedback loop - outputs to cortex tend to go back to sources
116
cerebellar fx
detect and reduce discrepancy between intended and actual actions
mainly understood as involved in motor response, but likely involved in other actions as well
117
anatomic divisions of cerebellum
lobe
- lobule
- - folia (run width of cerebellum, give distinctive texture)
118
is cerebellum ipsi or contralateral?
ipsilateral
119
functional distribution cerebellum
name indicates input:
vestibulocerebellum: vestibular inputs (and outputs)
- inferior cerebellar peduncle (ICP) input and output
- balance
- posture
- head position
- reflexive eye movements
spinocerebellum: input from spine and vestibular system
- ICP input
- SCP and ICP output (mostly to thalamus via SCP)
- limb movement
- extremity muscle tone
- balance and posture during movement
cerebrocerebellum: input from cerebral cortex via pons
- MCP input
- SCP output
- output dentate nucleus --> thalamus --> cortex
- coordination of precise movements
- cognition, higher cortical processing
120
deep cerebellar nuclei
```
3x
contain most output of cerebellum
- fastigial from vermis
- interposed from intermediate zone
- dentate from cerebrocerebellum
```
121
superior cerebellar peduncle
output to cortex via thalamus
| decussates in midbrain
122
middle cerebellar peduncle
input from cortex via pontine nuclei
pontocerebellar/transverse fibers
decussate before MCP
123
inferior cerebellar peduncle
input from spine, medulla, vestibular system
output to brainstem nuclei
most ipsilateral
124
purkinje cell
output cell of cerebellum
inhibitory
intrinsically active
inhibition --> target excitation
125
vestibulocerebellum
- vestibular inputs (and outputs)
- inferior cerebellar peduncle (ICP) input and output
- balance
- posture
- head position
- reflexive eye movements
126
spinocerebellum
- input from spine and vestibular system
- ICP input
- SCP and ICP output (mostly to thalamus via SCP)
- limb movement
- extremity muscle tone
- balance and posture during movement
127
cerebrocerebellum
- input from cerebral cortex via pons
- MCP input
- SCP output
- output dentate nucleus --> thalamus --> cortex
- coordination of precise movements
- cognition, higher cortical processing
128
ICP outputs of cerebellum
- immediate need
- vestibulospinal pathways: balance, posture
- reticulospinal pathways: eye movement, stability, control during movement
129
MCP outputs of cerebellum
none, input only (cortex > pons > cerebrocerebellum)
130
SCP outputs of cerebellum
- everything the ICP doesn't
- less immediate
- voluntary gaze (superior colliculus)
- other movements (thalamus > cortex)
- non-motor (thalamus > cortex)
131
red nucleus
feedback to inferior olivary nucleus
| an SCP output of cerebellum
132
superior colliculus
voluntary gaze
| an SCP output of cerebellum
133
basal ganglia fx
action production
| motor processes, likely non-motor as well
134
input basal ganglia
to striatum
from:
- excitatory: cerebral cortex
- dopaminergic: substantia nigra pars compacta (SNc), ventral tegmental area (VTA)
135
output basal ganglia
to globus pallidus internal segment (GPi)
| or substantia nigra pars reticularis (SNr)
136
direct pathway basal ganglia
facilitates action
137
indirect pathway basal ganglia
inhibits action
138
GPi neurons are (excitatory/inhibitory) and (constitutively active/inactive)
- inhibitory
- constitutively active
- "foot on the brake"
139
STN neurons are (excitatory/inhibitory) and (constitutively active/inactive)
- excitatory
| - inactive at baseline
140
dopamine receptors of direct and indirect pathways
```
direct = excitatory (net effect) = D1
indirect = inhibitory = D2
```
dopamine facilitates action in both cases:
- direct: increases drive
- indirect: inhibits inhibitory D2 receptors --> increases drive
141
posterior limb of internal capsule
white matter tract
| contains most ascending and descending pathways
142
anterior limb of internal capsule
white matter tract
| contains only ascending and descending pathways going to/from frontal pole and medial prefrontal cortex
143
semicircular canals
proprioception- angular acceleration
| inner ear
144
otolithic organs
proprioception - linear acceleration
utricle and saccule
inner ear
145
endolymph
surrounds hair cells in cochlea
| high K+ concentration (K+ influx depolarizes hair cell)
146
ossicles
middle ear
bones
malleus, incus, stapes
147
middle ear
ossicles
| connection to Eustachian tube
148
cochlear nuclei
carry info from one ear
| only part of CNS auditory pathway that only contains info from one ear
149
thalamus
relay station
| plus other stuff
150
supraoptic and paraventricular nuclei
produce ADH and oxytocin
| hypothalamus
151
preoptic nuclei
produce GnRH
| hypothalamus
152
suprachiasmatic nucleus
circadian rhythm
| hypothalamus
153
ventromedial nucleus
satiety
| hypothalamus
154
lateral nuclei
hunger
| hypothalamus
155
inputs to VPL
VPL = part of thalamus
- spinothalamic tract
- medial lemniscus
- trigeminal lemniscus
156
inputs to LG
LG = lateral geniculi = part of thalamus
- optic tract
157
inputs to MG
MG = medial geniculi = part of thalamus
- inferior colliculus
- lateral lemniscus
158
anterior nucleus
thermoregulation
| hypothalamus
159
semicircular canals
angular acceleration
works by inertia of circulating fluid within the canals
opposite canals (e.g. left and right horizontal) act as push-pull
160
otolithic organs
utricle and saccule
linear acceleration
mx similar to semicircular canals (inertia of fluid detected by hair cells) but anatomy/position better suited to detecting linear acceleration
also static tilt of head relative to gravity based on orientation of hair cells at rest
161
proprioceptive pathways
sensory organs:
- semicircular canals
- otolithic organs - utricle and saccule
vestibular nuclei
- inferior vn
- medial vn
- lateral vn
- superior vn
outputs of vn:
- cerebellum
- lateral vestibulospinal tract (LVST)
- medial VST (MVST)
- reticular formation
- thalamus
- cortex
- eye movement control nuclei
- contralateral vestibular nuclei
162
LVST
lateral vestibulospinal tract
cell bodies in lateral vestibular nucleus (LVN)
projects to IPSI-lateral spinal cord
* balance and posture
e. g. stumbling, feeling dizzy when you stop spinning
163
MVST
medial vestibulospinal tract
cell bodies in MVN
projects BI-laterally to upper cervical cord
* head position
164
thalamus and cortex in proprioception
vestibular nuclei --> BI-laterally to thalamus --> parietal cortex
165
step (eye movements)
sustained nerve activity/steady firing that maintains the eye in position
166
pulse (eye movements)
burst of rapid nerve firing that moves the eye
167
eye movement pathway
```
paramedian pontine reticular formation (PPRF)
- abducens nucleus
superior colliculus
frontal eye field (cortex)
primary motor cortex
```
horizontal eye movements:
- pons
vertical eye movements
- midbrain
168
saccadic eye movements
```
bring object of interest onto fovea, e.g. scanning a text or image
2-3x/second
generally automatic, can be voluntary
"ballistic"
physiologic
```
169
smooth pursuit eye movements
keep moving objects on fovea
driven by visual input
can be driven by *slow head movement
e.g. tracking moving finger, following car
170
vergence eye movements
convergence or divergence
| focuses/detects depth
171
VOR
vestibulo-ocular reflex
coordinates ocular movement with proprioception
*keeps focus on one object/doll eyes
e.g. eyes move right when head moves left to keep looking "forward"
172
nystagmus
can be physiologic or pathological
rapid, repeated eye movements
physiologic: if eye rotates too far in one direction, it springs to center
- also caloric nystagmus, which responds to change in temperature in one ear
pathologic: this happens too often/repeatedly; slow phase generally is the underlying disorder (e.g. eye drift)
directionality (L/R) defined by direction of fast phase (spring back)
173
decussation of optic nerve / tract
partial decussation in optic chiasm
each cerebral hemisphere covers contralateral hemifield
- L side of L eye (lateral) and L side of R eye (medial) both covered by R hemisphere
- t/f lateral/temporal hemifield will be ipsilateral while medial/nasal hemifield will be contralateral
174
pretectum
in midbrain
| pupillary light reflex
175
what makes aqueous humor (eye)
ciliary epithelium
176
what controls accommodation (lens)
ciliary muscle
177
flow of aqueous humor
produced: ciliary body
flow: pupil
exit: anterior chamber angle
angle closure --> extremely high IOP
178
dopamine metabolism
DA --> DOPAC via MAO
| DOPAC --> HVA (end-product) via COMT
179
activating dopamine receptors
D1, D5
180
inhibitory dopamine receptors
D2-4
