Neuro Flashcards
(531 cards)
1
Q
What is an action potential?
A
a sudden change in the voltage across a cell surface membrane due to the flow of certain ions in and out of the neuron
2
Q
at the resting membrane potential, is the inside of the cell more or less negative?
A
more
3
Q
What is the resting membrane potential?
A
the difference in electrical charge between the inside and the outside of the cell when it is at rest
4
Q
What is the value for the RMP for neurons?
A
-70mV
5
Q
Do all cells have the same RMP?
A
no
6
Q
is K+ found at a higher concentration inside or outside the cell?
A
inside
7
Q
are Na and Cl- found at higher concentrations inside or outside the cell?
A
outside
8
Q
Which ion has the greatest impact on the RMP?
A
K+
9
Q
How is the RMP maintained?
A
Na+ K+ ATPase
Actively pumps 3Na+ out, 2K+ in
10
Q
Which ion is the membrane predominantly permeable to?
A
K+
11
Q
Where does the action potential begin?
A
axon hillock (conical projection between the cell body and axon)
12
Q
what happens during depolarisation?
A
voltage gated sodium ion channels open due to an electrical stimulus
fast influx of sodium ions to +30mV
their positive charge changes potential within the cell from negative to more positive
13
Q
what is the threshold potential?
A
the value of membrane potential that must be reached by depolarisation for an action potential to be initiated
14
Q
what is the value of the threshold potential?
A
-55mV
15
Q
what does ‘all or nothing’ mean
A
if the threshold potential is reached, a response of the same magnitude is initiated regardless of the strength of the stimulus
16
Q
what happens once the cell has been depolarised?
A
voltage gated sodium ion channels begin to close
17
Q
why do voltage gated potassium channels open?
A
the potential within the cell is positive
18
Q
what is repolarisation?
A
voltage gated potassium channels open
K+ ions leave the cell down their electrochemical gradient
the membrane potential becomes more negative and approaches the resting potential
19
Q
what is hyperpolarisation?
A
repolarisation overshoots the resting potential
K+ channels are open slightly too long
the membrane potential becomes more negative
20
Q
is Na+/ K+ ATPase involved in repolarisation?
A
no
21
Q
what is a refractory period, and what are the two divisions?
A
time following an action potential
absolute refractory period
relative refractory period
22
Q
when does the absolute refractory period occur
A
occurs when sodium channels close after an action potential
sodium channels cannot be opened regardless of the membrane potential
23
Q
when does the relative refractory period occur?
A
sodium channels slowly come out of inactivation
action potentials can occur if the stimulus is large enough
24
Q
what is saltatory conduction?
A
myelinated regions of the axon are not depolarised
25
why do action potentials only flow in one direction?
the refractory period
26
how are action potentials propagated along axons?
local currents flow following depolarisation and allow depolarisation of adjacent axonal membranes
27
what factors determine how far local currents travel?
capacitance and resistance
28
what is capacitance?
ability to store charge
29
how does capacitance affect the distance travelled by a local current?
a lower capacitance means a greater distance travelled
30
what is resistance?
number of ion channels open
31
how does myelin increase conducting speeds?
decreases capacitance and increases resistance
32
how does resistance affect the distance travelled by a local current?
a higher resistance means fewer ion channels open
means a greater distance travelled
33
what does osmium stain?
white matter/ myelin black
34
what stains myelin, and what colour?
osmium
black
35
what are the myelinating cells of the CNS?
oligodendrocytes
36
what are the myelinating cells of the PNS?
Schwann cells
37
what is MS?
immune system attacks the myelin sheath
saltatory conduction is disrupted
symptoms
- uncontrolled eye movement
- slurred speech
38
What is Guillain Barre Syndrome?
damage to PNS myelin
autoimmune
muscle weakness and pain
39
what is synaptic transmission?
process by which neurons communicate with each other
40
what are the types of synaptic transmission?
chemical (more common) and electrical
41
describe electrical synaptic transmission
gap junctions join pre and post synaptic clefts
very rapid adjacent depolarisation
42
give an example of where you can find an electrical synapse
brainstem e.g hypothalamic hormone secretion
43
describe a chemical synapse
5 stages
- manufacture
- storage in vesicles
- release
- activation at post synaptic receptors
- inactivation - breakdown or re-uptake
44
what is an EPSP?
a postsynaptic potential that propagates an action potential and results in depolarisation
excitatory post synaptic potential
45
what is an IPSP?
a postsynaptic potential that inhibits an action potential and results in hyperpolarisation
inhibitory post synaptic potential
46
Is the NMJ always, sometimes or never excitatory?
always
47
what is an excitatory neurotransmitter?
membrane potential of postsynaptic neuron depolarised
48
what is an inhibitory neurotransmitter
membrane potential of postsynaptic neuron hyperpolarised or stabilised at resting potential
49
what are the two types of summation?
spatial and temporal
50
why is summation required?
one EPSP is not enough to reach the action potential threshold
51
what is spatial summation?
integration of neurotransmitter signals from several presynaptic neurones to one post synaptic neurone
52
what is temporal summation?
input signals arrive from the same presynaptic cells at different times
53
how are neurotransmitters removed?
3 methods
actively reuptaken back to presynaptic axon terminal
diffuse away from receptor site
enzymatically transformed into inactive substances
54
Give examples of fast neurotransmitters
Ach
glutamate
GABA
55
Is Ach excitatory, inhibitory or both?
Both
56
Where is Ach excitatory?
Skeletal muscle
57
Where is Ach inhibitory
cardiac muscle
58
what is the main excitatory neurotransmitter
GLUT
glutamate
59
what is the main inhibitory neurotransmitter
GABA
60
Give examples of slow neuromodulators
NAd (norepinephrine/ noradrenaline)
DA (dopamine)
Serotonin
61
which neurotransmitter has a major function at the NMJ?
Ach
62
what are the main types of receptors of Ach?
nicotinic and muscarinic
63
what do nicotinic receptors respond to?
ACh and nicotine
64
which receptor is found at the NMJ?
nicotinic
65
where do muscarinic receptors work?
where PNS innervates peripheral organs and glands
e.g salivary glands and
66
are nicotinic receptors metabotrophic or ionotrophic?
ionotrophic
67
are muscarinic receptors metabotrophic or ionotrophic?
metabotrophic
68
what is the action of AchE
Acetylcholinesterase
Breaks down Ach to acetate + choline after function in the synaptic cleft
69
which neurotransmitter is important in the peripheral heart and CNS?
Noradrenaline
70
what affects noradrenaline?
antidepressant drugs
stimulants
71
what affects serotonin?
antidepressant SSRI drugs (e.g Prozac)
ecstasy
72
which neurotransmitter is vital in basal ganglia?
dopamine
73
where are most dopaminergic neurons?
substantia nigra
74
what affects dopamine?
antipsychotics
stimulants
Parkinson's medication
75
what is an ascending tract?
neural pathway by which sensory information from peripheral nerves is transmitted to the cerebral cortex
76
how are ascending tracts divided?
conscious and unconscious
77
what comprises conscious tracts?
dorsal column-medial lemniscal pathway (DCML) and the spinothalamic tract (anterolateral system)
78
what comprises unconscious tracts?
spinocerebellar tracts
79
why does the DCML have that name?
information travels through dorsal columns in spinal cord then transmitted through medial lemniscus in brainstem
80
describe the DCML
fine sensation detected by receptors
afferent signals carried along 1st oder neurones to dorsal columns and up to medulla where they synapse
second order neurones decussate in medulla and travel up to thalamus where they synapse
3rd order neurones travel through internal capsule to somatosensory cortex
81
what are the names of the groups of neurones that comprise the DCML?
first, second and third order neurones
82
what does the DCML carry the sensory modalities of?
fine touch, vibration, proprioception
83
what do first order neurones of the DCML do?
carry sensory information (regarding touch, proprioception or vibration) from the peripheral nerves to the medulla oblongata
84
where do DCML first order neurons travel in?
2 versions
fasciculus cuneatus for upper limb - lateral part
fasciculus gracilis for lower limb - medial part of dorsal column
this is in the spinal cord
85
where do second order neurones of the DCML begin?
gracile OR cuneate nucleus in medulla
86
what do second order neurones of the DCML do?
receive information from preceding neurones and deliver it to third order neurones in the thalamus
87
where do second order neurons of the dcml synapse?
medulla
88
where do fibres of second order neurones of the DCML desuccate?
medulla oblongata
travel to contralateral thalamus
89
what do third order neurones of the DCML do?
transmit the sensory signals from the thalamus to the ipsilateral primary sensory cortex of the brain
90
where do signals from the upper limb travel?
in the fasciculus cuneatus (the lateral part of the dorsal column)
91
what vertebral segments count as the upper limb?
T6 and above
92
what vertebral segments count as the lower limb?
T6 and below
93
where do signals from the lower limb travel?
in the fasciculus gracilis (the medial part of the dorsal column)
94
where do fibres from the upper limb synapse?
nucleus cuneatus of the medulla oblongata
95
where do fibres from the lower limb synapse?
nucleus gracilis of the medulla oblongata
96
in the DCML, how does information travel in the spinal cord?
via dorsal columns
97
in the DCML, how does information travel in the brainstem?
via the medial lemniscus
98
what are the two tracts of the anterolateral system?
anterior spinothalamic tract
lateral spinothalamic tract
pathways are the same for both tracts
the tracts run alongside each other
99
what are the names of the groups of neurones in the anterolateral system?
first, second and third order neurones
100
what is the function of the anterior spinothalamic tract?
crude touch and pressure
101
what is the function of the lateral spinothalamic tract
pain and temperature
102
where do the first order neurones of the spinothalamic tracts arise from?
sensory receptors in the periphery
103
where do first order neurones of the spinothalamic tracts travel after they have arisen
enter spinal cord
104
where do first order neurones of the spinothalamic tracts synapse?
tip of the dorsal horn
105
what do second order neurones of the spinothalamic tracts do?
carry information from the dorsal horn to the thalamus
106
where do second order neurones of the spinothalamic tracts desuccate?
spinal cord
107
what do third order neurones of the spinothalamic tracts do?
carry information from the thalamus to the ipsilateral primary sensory cortex
108
describe the spinothalamic pathway
nociceptors or thermoreceptors detect pain, temperature or crude touch
1st order neurons carrying these signals enter spinal cord and ascend 2-3 levels before synapsing in dorsal horn of grey matter
2nd order neurones decussate either through anterior or lateral tracts then travel up to thalamus where they synapse
3rd order neurones travel through the internal capsule to the primary somatosensory cortex
109
what are spinocerebellar tracts?
groups of tracts carrying unconscious proprioceptive information from the muscles to the cerebellum
110
what are the 4 spinocerebellar tracts?
posterior spinocerebellar, cuneocerebellar, anterior spinocerebellar, rostral spinocerebellar
111
where does the posterior spinocerebellar tract carry information from?
lower limbs to ipsilateral cerebellum
112
where does the cuneocerebellar tract carry information from?
upper limbs to ipsilateral cerebellum
113
where does the anterior spinocerebellar tract carry information from?
lower limbs to ipsilateral cerebellum
114
how many times do fibres in the anterior spinocerebellar tract dessucate?
twice
meaning they end up where they started so the fibres go to thee ipsilateral cerebellum
115
spinoreticular tract
deep/ chronic pain
116
where does the rostral spinocerebellar tract carry information from?
upper limbs to ipsilateral cerebellum
117
what are descending tracts?
pathways by which motor signals are sent from the brain to the spinal cord
118
what are the divisions of the descending tracts?
pyramidal and extrapyramidal
119
where do pyramidal tracts originate?
cerebral cortex
120
what do pyramidal tracts do?
carry motor fibres to spinal cord and brainstem from cerebral cortex
121
what are pyramidal tracts responsible for?
voluntary control of musculature
makes sense as they come from cerebral cortex
122
where do extrapyramidal tracts originate?
brainstem
123
what do extrapyramidal tracts do?
carry motor fibres to the spinal cord
124
what are extrapyramidal tracts responsible for?
involuntary and autonomic control of musculature
e.g muscle tone, balancee, posture, locomotion
125
what are the two divisions of pyramidal tracts?
corticospinal and corticobulbar
126
inputs of corticospinal tracts
primary motor cortex, premotor cortex, supplementary cortex
127
describe the path of the corticospinal tracts
begins in the cerebral cortex, descends through the corona radiata to the internal capsule, crus cerebri, pons, medulla
128
in which part of the medulla do the corticospinal tracts divide into 2?
caudal
129
where do corticospinal tracts terminate
ventral horn of spinal cord
130
what is the path of the lateral corticospinal tract?
desuccates and then descends, terminating in the ventral horn
131
what is the path of the anterior corticospinal tracts?
remain ipsilateral to the spinal cord, then desuccates and terminates in the ventral horn of the upper thoracic levels
132
describe corticospinal tracts
originate in primary motor cortex
descend through corona radiata and internal capsule to medullary pyramids
90% decussate to bceomee the lateral corticospinal tract
remaining 10% forms the anterior corticospinal tract
anterior tract then decussates through the anterior white commisure
both tracts terminate in the ventral horn
133
what does the corticospinal tract control?
motor control of the body muscles
anterior - axial muscles
lateral - limb muscles
134
what does the corticobulbar tract control?
motor control of the face and neck muscles
135
what are the two types of neurones in the descending tracts?
upper and lower motor neurones
136
where do the corticobulbar tracts begin?
lateral aspect of the primary motor cortex
137
inputs of the corticobulbar tracts
primary motor cortex, premotor cortex, supplementary cortex
138
path of the corticobulbar tracts
primary motor cortex, descend through internal capsule, crus cerebri, brainstem, terminate on motor nuclei of cranial nerves (acting on facial and neck muscles)
synapse with LMNs which carry motor signals to the face and neck
139
which nerves are the only two to not innervate motor neurons bilaterally?
facial and hypoglossal nerve have contralateral innervation
140
do the upper motor neurones facial and hypoglossal nerves only provide contralateral innervation?
hypoglossal - yes
facial - contralateral below the eyes
141
how can you tell the difference between an upper and lower motor neurone lesion
see if there bottom of the face can move (means UMN lesion - stroke rather than Bell's palsy)
142
what are the types of extrapyramidal tracts?
vestibulospinal, reticulospinal, rubrospinal, tectospinal
143
where does the vestibulospinal tract arise from?
vestibular nuclei
144
where does the medial reticulospinal tract originate from?
pons
145
where does the lateral reticulospinal tract originate from?
medulla
146
where does the rubrospinal tract originate from?
red nucleus
147
where does the tectospinal tract originate from?
superior colliculus
148
which extrapyramidal tracts desiccate?
rubrospinal and tectospinal
149
role of vestibulospinal tracts
balance and posture
150
role of medial reticulospinal tracts
voluntary movement and increasing muscle tone
151
role of lateral reticulospinal tracts
inhibits voluntary movement and reduces muscle tone
152
role of rubrospinal tracts
fine control of hand movements
originate from rd nucleus
153
do rubrospinal or tectospinal tracts enter the spinal cord after dessucating?
tectospinal
154
role of tectospinal tracts
coordinates movements of the head in relation to vision stimuli
155
are there synapses in the descending pathways?
no
all the neurons within the descending motor system are UMNs, and they synapse with a LMN
156
what does the ANS innervate?
smooth and cardiac muscle, glands
157
what does the somatic nervous system innervate?
skeletal muscle
158
which neurotransmitter do somatic nerves use?
ACh
159
do somatic efferent nerves have one or two axons between the CNS and skeletal muscle cell?
one
160
where are cell bodies of the somatic nervous system?
brainstem or ventral horn of spinal cord
161
do somatic efferent neurons synapse from the CNS to muscle?
no
162
what is the only neurotransmitter for somatic efferent neurones to use?
Ach - only excitatory
163
how many axons do autonomic efferent neurones use?
2 (pre and post ganglionic)
164
what neurotransmitters do preganglionic neurones use?
always Ach
165
what neurotransmitters do postganglionic neurones use?
Ach - excitatory
NAd - inhibitory
166
what segment of the spinal cord supplies sympathetic innervation?
T1-L2
thoraco-lumbar
167
where does a sympathetic neurone synapse
lateral horn
168
do sympathetic neurones have a long or short preganglionic axon?
short
169
do parasympathetic neurones have a long or short preganglionic axon?
long
170
functions of the autonomic nervous system
thermoregulation, exercise, digestion, competition, sexual function
171
where are the nuclei of the parasympathetic cranial nerves located?
brainstem
172
which cranial nerves are parasympathetic?
10,9,7,3 (remember by 1973)
173
what is the role of cranial nerve 10 in a parasympathetic response?
decreases heart rate, vasoconstriction, increases GI motility
174
which types of receptor and neurotransmitters are used in the parasympathetic nervous system?
Ach to nicotinic
then
Ach to muscarinic
175
which types of receptor and neurotransmitters are used in the sympathetic nervous system?
Ach to nicotinic
then
NAd to adrenergic
176
what are the roles of cranial nerves 7 and 9 in a parasympathetic response?
9 - swallowing
7 - salivary glands
177
what is the role of cranial nerve 3 in a parasympathetic response?
pupil constriction
178
what is the enteric nervous system?
involved with the GI tract
can operate independently (autoregulation)
179
what is a motor unit?
a SINGLE motor neuron and all the muscle fibres it innervates
180
what happens to the adjacent motor units when on his damaged?
get bigger
181
where does an UMN travel from?
motor cortex to spinal cord
182
where does a LMN travel from?
spinal cord to muscle
183
what are the consequences of an UMN lesion?
hypertonia
hyperreflexia
spasticity
positive Babinski sign
clonus
184
what is a positive Babinski sign?
touch sole of foot with object
foot's big toe extends rather than flexes
185
consequences of a LMN lesion
hyporeflexia
hypotonia
fasciculations (small twitch)
muscle atrophy
186
can a muscle cell be innervated by more than one neurone?
no
187
can a neurone innervate more than one muscle cell?
yes
188
what is an end plate potential?
voltages which cause depolarization of skeletal muscle fibers caused by neurotransmitters binding to the postsynaptic membrane in the neuromuscular junction.
189
what is a muscle spindle?
proprioceptors that consist of intrafusal muscle fibers enclosed in a sheath
intrafusal + stretch receptor
190
where are muscle spindles found and what do they do?
deep in muscle, detect stretch
191
what is the efferent supply of muscles?
by gamma (Y) neurones
192
what is the afferent supply of muscles?
1a fibres
193
what are Golgi tendons?
tension receptors
194
what fibres do Golgi tendons associate with?
1b fast fibres
195
what spinal nerve segments does the patellar reflex test?
L2-L4
196
describe the patellar reflex
patella knocked
activates stretch receptors in all knee
1a from intrafusal fibres to CNS (spinal cord)
A) monosynaptic excitatory stimulation of quadriceps - knee jerk (extension)
B) polysynpatic - inhibition of flexors of knee, excitation of synergistic muscles at knee
1b from Golgi tendon to CNS
C) polysynaptic inhibition of knee jerk when too much stretch detected (prevents overextension and injury)
inverse myotactic reflex
197
what is a motor unit?
an alpha motor neuron and all the extrafusal skeletal fibres it innervates
198
what is the effect of having an alpha motor neurone innervating fewer skeletal fibres?
finer regulation
199
how are motor neurones somatotrophically organised in the spinal cord?
alpha motor neurones in the lateral portion control distal muscle
alpha motor neurones in the medial portion control proximal muscle
200
what is the spinothalamic tract?
sensory tract that carries nociceptive, temperature, crude touch, and pressure from our skin to the somatosensory area of the thalamus
part of the anterolateral system
201
function of nociceptors
sense pain
202
function of the anterior spinothalamic tract
crude touch, pressure, slow pain
203
function of the lateral spinothalamic tract
pain and temperature
204
are alpha fibres myelinated?
yes
205
are C fibres myelinated?
no
206
analgesia vs anaesthetic
analgesia
- selective pain suppression
- consciousness not affected
anaesthetic
- total pain suppression
- consciousness can be affected
207
Parkinson's
loss of substantia nigra
cannot initiate movement
208
Myesthenia gravis
ACh at neuromuscular junction blocked
muscle weakness
209
berry aneurysms
caused by weakened blood vessel
210
Duchennes
X linked
muscular degradation
recessive
211
Brown Sequard
hemisectional spinal cord compression
e.g lesion below medulla and above spinothalamic decussation
- ipsilateral motor dysfunction
- ipsilateral touch, vibration, proprioception and two point discrimination dysfunction
- contralateral pain, temperature and crude touch dysfunction
212
Huntington's
low GABA
high dopamine
opposite of Parkinson's, too much overshooting movement
full penetrance, autosomal dominant, anticipation
213
multiple sclerosis
myelin scarring
214
embryology of the brain
after week 3, gastrulation
- formation of trilaminar disc
ectoderm differentially mitoses
neural groove formed
neural tube formed
neural crest cells lateral to neural tube - differentiate into brain and CNS
215
what is the prosencephalon?
forebrain
216
what is the mesencephalon?
midbrain
217
what is the rhombencephalon?
hindbrain
218
what is the prosencephalon divided into?
telencephalon and diencephalon
219
what comprises the telencephalon?
cerebral hemispheres and basal ganglia
220
what comprises the diencephalon?
thalamus, sub thalamus, hypothalamus, epithalamus
221
what comprises the rhombencephalon?
pons, cerebellum, medulla oblongata
222
what macromolecules form the myelin sheath?
lipid and protein
223
when does myelination begin?
in utero
3rd trimester
224
does myelination appear as white or grey matter?
white
225
which neurons tend to be unmyelinated
post ganglionic autonomic fibres
olfactors neurones
interneurones
226
Guillain-Barre Syndrone
rapid onset of muscle weakness
autoimmune damage to PNS
myelin sheath damaged
pain and weakness
227
space between membranes of pre and post synaptic membranes
synaptic cleft
228
end of axon
axon terminal
229
types of synapse, and which is more common
chemical and electrical
chemical is more common
230
supporting cells of the nervous system
glial cells
231
type sof glial cells
astrocytes, oligodendrocytes, and microglial cells
232
describe chemical synapses
plasma membranes of pre and postsynaptic cells are joined by synaptic cleft
axon ends in axon terminal
synaptic cleft prevents direct propagation of the current
signals are transmitted via chemical messenger
synpases are covered by astrocytes, essential for reuptake of neurotransmitter
233
describe electrical synapses
plasma membranes of pre and postsynaptic cells are joined by gap junctions
local currents flow directly across junction
depolarises membrane of 2nd neuron to threshold potential
very rapid
234
where do we find electrical synapses?
brainstem neurons e.g hypothalamus for hormone secretion
235
which ion causes neurotransmitter release?
calcium
236
describe neurotransmitter release
voltage gated calcium channels open when action potential reaches pre-synaptic terminal
vesicles move to release sites and fuse with pre-synaptic membrane
exocytosis of neurotransmitter
237
two types of post-synaptic membrane receptors
ionotrophic and metabotrophic
238
nature of ionotrophic and metabotrophic receptors
ionotrophic - ligand gated ion channels
metabotrophic - G protein coupled receptors
239
response of activation of ionotrophic and metabotrophic receptos
ionotrophic - ion flux to change cell voltage
metabotrophic - acts via second messengers, causing cellular effects
240
which are faster, ionotrophic or metabotrophic receptors?
ionotrophic
241
which are longer acting, ionotrophic or metabotrophic receptors?
metabotrophic
242
give examples of uses of neuromodulators
learning
development
243
action of local anaesthetics
block sodium channels to prevent depolarisation
244
name of neurotransmitters that release ACh
cholinergic
245
how is ACh broken down?
by acetylcholinesterase into acetate and choline
246
fate of choline after production
transported back into presynaptic axon to be reused
247
how many vertebrae in total?
33
248
how many spinal nerves?
31
249
which spinal cord segments are fused?
sacral
coccyx
250
how many cervical vertebra?
7
251
which are the two uppermost vertebrae called?
C1 - altas
C2 - axis
252
how many thoracic vertebrae?
12
253
how many lumbar vertebrae?
5
254
how many sacral vertebrae?
5 fused to form the sacrum
255
how many coccyx vertebrae
4 fused
256
what happens when muscle fibres are depolarised?
actin and myosin slide over each other to produce muscle contraction
257
structure of skeletal muscle
actin and myosin myofibrils
form muscle fibres
form muscle fasciculi
258
features of cervical vertebrae
small vertebral body
transverse foramen
bifid spinous process bar C7
triangula rintervertebral foramen
259
which vertebrae have a transverse foramen, and what is the purpose?
cervical
contain vertebral artery and sympathetic chain
260
which is the only cervical vertebra not to have a bifid spinous process?
C7
261
prominent spike on C2
dens
262
which vertebrae have a circular vertebral foramen?
thoracic
263
which vertebrae contain costal facets?
thoracic
264
which vertebrae have a triangular vertebral foramen?
lumbar
265
which vertebrae have broad and thick spinous processes?
lumbar
266
what does the central canal of the spinal cord contain?
CSF
267
enlargements of the spinal cord
cervical - C3 -T1 to upper limb
lumbar - L1 - S3 to lower limb
268
where does the spinal cord end?
L1/L2
269
name for the tapering of the spinal cord to a cone
conus medullaris
270
name for the spinal cord tapering to a strand of tisse
filum terminale
271
what do axons in the dorsal cord convey?
afferent - sensory neurons
272
what do axons in the ventral cord convey?
efferent - motor neurons
273
how do cervical spinal nerves leave the spine?
1 vertebra higher except for C8 which is below
274
how do thoracic, lumbar and sacral nerves leave?
below the corresponding vertebra
275
how many pairs of spinal nerves, and how are they divided?
31
8 c
12t
5l
5s
1 coccygeal
276
what surrounds several nerve fascicles?
eepineurium
277
what surrounds each fascicle?
perineurium
278
what connects axons laterally in a fascicle?
endoneurium
279
larger bundles of fascicles
funiculi
280
what does silver stain?
grey matter black
281
what stains grey and white matter, and what colours? what does this correspond to?
grey matter - cell bodies
stained black by silver
white matter - axoms/ myelin
stained black by osmium
282
how many dorsal and ventral horns?
2 of each
283
which nerve and spinal segments control penis erection?
S2, S3, S4 pudendal nerve
284
ankle, knee, wrist and biceps, triceps reflexes
ankle - S1, S2
knee - L3, L4
wrist and biceps - C5, C6
triceps - C7, C8
285
where is the cell body of the first ANS neuron?
in the CNS
286
can the ANS be both excitiatory and inhibitory?
yes
287
which neurotransmitters are used in the ANS and when?
ach before ganglion
ach (excitatory) or noradrenaline (inhibitory) after
288
effects of sympathetic nervous system
increased heart rate
vasoconstriction
reduced gastric motility
289
are ejactulation and erection parasympathetic or sympathetic?
ejaculation is sympathetic
erection is parasympathetic
290
where is parasympathetic outflow from?
brainstem and sacral vertebrae
291
which neurotransmitter is used at the effector for parasympathetic, somatic and sympathetic nerves?
para - ACh
sympathetic - NE
somatic - ACh
292
is the preganglionic or post ganglionic nerve of ANS myelinated?
pre
293
do parasympathetic or sympathetic neurons have a longer preganglionic axon?
parasympathetic
294
what is a motor unit?
alpha motor neuron and all the extrafusal skeletal muscle fibres it innervates
295
do medial or lateral alpha motor neurons control distal muscles?
lateral
296
what is muscle tone?
degree of contraction of a muscle or the proportion of motor units that are active at a time
297
region of muscle fibre directly under the terminal portion of the motor neuron
motor end plate
298
junction between the axon terminal and motor end plate
neuromuscular junction
299
what is an EPP
end plate potential
comparable to EPSP
300
describe the NMJ
action potential arrives at axon terminal
plasma membrane depolarised
voltage gated calcium channels open
calcium ions diffuse into the axon terminal
ACh vesicles ruse with the neuronal plasma membrane
ACh diffuses to the motor end plate and binds to cholinergic nicotinic receptors
ion channels in the receptor protein opens
more Na moves in than K out
EPP produced
301
upper motor neuron
cell body originates in the cerebral cortex or brainstem
terminates within the brainstem or spinal cord
302
symptoms of upper motor neuron damage
hypertonia
hyperreflexia
spasticity
positive babinski's sign
clonus
303
can a lower motor neuron innervate more than one muscle fibre?
yes but not the other way round
304
types of lower motor neuron
alpha and gamma
305
function of alpha motor neurons
contraction of muscle fibres
306
which motor neurons are somatotrophically organised?
alpha
307
which motor neurons exhibit signs of LMN syndrome when damaged?
alpha
308
function of gamma motor neurons
regulation of muscle tone
proprioception
309
symptoms of LMN damage
hypotonia
hyporeflexia
flaccid muscle weakness or paralysis
fasciculation - small involuntary twitches
muscle atrophy
310
function of stretch receptors
monitor muscle length and rate of change of muscle length
311
what is a muscle spindle?
intrafusal fibres embeddd in muscle - extrafusal fibres
312
what are intrafusal fibres (in muscle spindles) innervated by?
gamma motor neurons
313
function of gamma motor neurons in the intrafusal fibres
keep the intrafusal fibres at a set length to optimise muscle stretch detection
314
types of stretch receptors
nucelar chain and nuclear bag
315
function of nuclear chain receptors
respond to how much the muscle is stretched
316
function of muscle bag receptors
respond to magnitude and speed of stretching
317
what part of the muscle spindle are contractile?
2 ends
centre is non-contractile
318
which part of the spindle is associated with fast type 1a afferent sensory nerves?
middle third
non contractile part
319
which part of the spindle is associated with type 2 afferent sensory nerves that are slower conducting?
inferior and superior parts
320
what are muscle spindle attached to in paralell?
extrafusal fibres
321
what does muscle tension depend on?
muscle load
muscle length
degree of muscle fatigue
322
what detects muscle tension?
golgi tendon organ
323
what do golgi tendon organs detect?
force developed by muscle and resultant change in length
324
what is the Golgi tendon organ?
endings of afferent fibres that wrap around collagen bundles in the tendons
325
which fibres run from the golgi tendon organ?
afferent 1b sensory nerve fibres
- inhibitory
326
how do golgi tendon organs work?
when the muscle is stretched, tension is exerted on the tendon
the bundles straighten and activate the GTO receptor endings
327
what do golgi tendon organs stimulate and inhibit?
stimulate motor neurons of the antagonistic muscle
inhibit alpha motor neurons to prevent muscle contraction
328
function of 1b fibres
inhibit muscle contraction via inhibiting alpha motor neurons
329
what is the stretch reflex called?
myotatic
330
patellar reflex
stretch reflex
patellar tendon is tapped
thigh muscle stretch
stretch receptors activation
burst of action potentials in the afferent nerve fibres
stimulation of motor unit
muscle contraction
extension of lower leg
331
is the patellar reflex monosynaptic?
yes
332
what is a polysynaptic reflex?
at least one interneuron between the afferent and efferent neurons
333
reciprocal innervation
afferent nerve fibres end on inhibitory interneurons
when activated, they inhibit the motor neurons of the antagonistic muscle
e.g with the patellar reflex, the neurons that flex the knee would be inhibited
334
withdrawal reflex
pain stimulation activates flexor muscles and inhibits extensor muscles
affected limb moves away from harmful stimulus
335
example of withdrawal reflex
touching something hot
336
withdrawal reflex in the leg
shift in weight
motor neurons to the contralateral extensors aree activated, and the flexors are inhibited
337
acute pain last how long
less than 12 weeks
338
how long is chronic pain?
over 12 weeks
339
nociceptive pain
arises from actual or threatened damage to non-neuronal tissue
340
neuropathic pain
caused by primary lesion/ dysfunction of the nervous system
341
pain pathway to brain
first order neuron remains ipsilateral? and synapses with second order neuron
second order neuron cell body is in the spinal cord/ brainstem
it decussates and ascends to the thalamus
third order neuron cell body is in the thalamus
axons project to somatosensory cortex
342
internal nociceptors
viscera
joints
muscles
343
external nociceptors
mucosa
skin
cornea
344
what can cause hyperalgesia?
bradykinin
prostaglandin E2
345
what is hyperalgesia?
reduced nociceptive action potential threshold
increased sensitivity to pain
346
types of nociceptors
alpha delta fibres
C fibres
347
smallest nerve fibres
C fibres
348
which nerve fibres have a high activation threshold?
alpha delta
349
what type of pain are alpha delta fibres responsible for?
and C fibres?
quick and localised pain
slow spread out pain
350
myelination of alpha delta fibres
thinly myelinated
351
myelination of C fibres
none
352
are alpha delta or C fibres fast?
alpha delta
353
what information do alpha delta fibres carry?
touch, pressure, temperature
354
what do alpha delta fibres release?
glutamate
355
what information do C fibres carry?
pain, temperature, touch, pressure, itch
356
what do C fibres release?
glutamate and substance P
357
what is substance P and its function?
peptide neurotransmitter and vasodilator
remains bound to receptors for a longer time, causing long lasting pain
358
analgesia
selective suppression of pain without effects on consciousness
359
anaesthesia
uniform suppression of pain
no pain is felt
can cause loss of consciousness
360
brain development
fertilisation
morula - 16 cells
blastocyst - over 16 cells
trilaminar disc
- ectoderm
- mesoderm
- endoderm
ectoderm thickens in the midline to form the neural plate in the 3rd week
neural groove formed
groove deepens to form neural tube by end of 4th week
361
where are neural crest cells?
lateral to neural plate
362
what do neural crest cells form?
ganglia
Schwann cells
adrenal medulla
meninges
dermis
CN 5, 7, 9, 10
363
when do primary and secondary brain vesicles form?
5th and 7th week
364
when does the blood brain barrier form?
8 weeks
365
cells of blood brain barrier
endothelial cells, pericytes, astrocytes
366
when does the neural tube close?
end of week 4
367
failure of neural tube to close in spinal cord
spina bifida
368
failure of neural tube to close in cephalic region
anencephalus
369
functions of frontal lobe
thought, memory, reasoning
370
which areas make up Broca's area?
Brodmann's area 44 and 45
371
only sensation not to relay through thalamus
olfactory
372
which gyrus is linked to limbic system?
cingulate
373
where is the degree of pain judged?
insula
374
grey matter in the midbrain around the cerebral acqueduct
periaqueductal grey
375
dorsal striatum
caudate nucleus and putamen
376
ventral striatum
nucelus accumbens and olfactory tubercle
377
parts of basal ganglia
caudate nucleus, putamen, nucleus accumbens, olfactory tubercle, globus pallidus, ventral pallidum, substantia nigra, subthalamic nucleus
378
basal ganglia disorders
parkinsons
huntingtons
379
lack of dopamine
parkinsons
380
excess dopamine
huntingtons
381
Parkinson's
loss of dopaminergic neurons in substantia nigra
spacicity, reduced movement, bradykinesia, tremor
382
parkinson's treatment
L Dopa
corrects dopamine deficiency
383
Huntington's
cag repeats
too little GABA results in too much dopamine
autosomal dominant
full penetrance
dementia and personality change
destruction of the striatum - in particular the caudate nucleus
384
function of basal ganglia
posture, motor control, behavior
385
function of limbic system
interface between the internal and external environment
adaptive behavior, emotional responsiveness
386
parts of limbic system
cingulate gyrus, hippocampus, parahippocampal gyrus, anterior perforated substance, septal nuclei, uncus, amygdala
387
what connects the parts of the limbic system
papez circuit
388
function of amygdala
fear and reward
389
function of septal nuclei
reward and reinforcement
390
function of hippocampus
short term memory, spatial memory, navigation
391
function of papez circuit
emotional expression and memory
392
what does the papez circuit start and end with?
hippocampus
393
papez circuit
hippocampal formation, fornix, mamillary bodies, mammilothalamic tract, anterior thalamic nucleus, cingulum, entorhinal cortex, hippocampal formation
394
a disease of the papez circuit/ limbic system
Alzheimers
395
where is memory stored?
prefrontal cortex
396
function of hypothalamus
homeostasis
397
explicit memory
conscious
398
types of explicit memory
episodic and semantic
399
what is episodic memory?
autobiographical
hippocampus and midbrain
400
what is semantic memory?
knowledge
frontal temporal lobe
401
hat is implicit memory?
unconscious
skills and habits - cerebellum and basal ganglia
conditioned reflexes - cerebellum
emotion - amygdala
402
functions of cerebellum
motor control of equilibrium
maintenance of posture and balance
maintenance of muscle tone
coordination of voluntary movements
403
cerebellar tracts
corticopontocerebellar
vestibulocerebellar
spinocerebellar
404
where does the corticopontocerebellar tract receive information from and signal to?
primary motor cortex
middle cerebellar peduncle
405
where does the vestibulocerebellar tract receive information from and signal to?
vestibular impulses from labyrinths via the vestibule nucleus
to the inferior cerebellar peduncle
406
where does the spinocerebellar tract recieve information from and signal to?
sensory input for balance and position sense
superior cerebellar peduncle
407
layers of cerebellum out to in
molecular, purkinje, granule
408
symptoms of cerebellar damage
jerky and erratic movement
409
on which aspect of the midbrain are the colliculi and pineal?
dorsal
410
where do each pair of cranial nerves emerge?
The oculomotor nerve (III) and trochlear nerve (IV) emerge from the midbrain, the trigeminal (V), abducens (VI), facial (VII) and vestibulocochlear (VIII) from the pons, and the glossopharyngeal (IX), vagus (X), accessory (XI) and hypoglossal (XII) emerge from the medulla.
411
where is the locus coerulus?
lateral floor of 4th ventricle
412
function of locus coerulus
sleep-wake
attention and memory
stress
emotions
413
fissurres of the medulla
anterior median fissure
ventrolateral sulcus
posterolateral sulcus
414
what decussates at the medulla?
pyramids
DCML
415
where are the olives?
medulla
416
function of the medulla
autonomic
ventilation
417
which cranial nerves are parasympathetic?
1973
10th 9th 7th 3rd
418
innervation and function of hypoglossal
exit foramen
intrinsic and extrinsic muscles of the tongue
movement of the tongue
hypoglossal canal
419
how to tell which cranial nerves are sensory, motor or both
some say marry money but my brother says big brains matter more
420
innervation and function of accessory nerve
exit foramen
sternocleidomastioid and trapezius
movement of head and shoulders
421
innervation and function of vagus
exit foramen
a lot
pharynx, larynx, trachea, oesophagus
viscera
soft palate
general sensation
chemoreception
speech
swallowing
cardiac muscle innervation
and more
jugular foramen
422
innervation and function of glossopharyngeal
exit foramen
pharynx, posterior third of tongue, eustacian tube, middle ear, carotid body, carotid sinus, stylopharyngeus, parotid
taste, chemoreption, baroreception, swallowing, salivation
jugular foramen
423
function of vestibulocochlear nerve
innervates vestibular apparatus
position and movement of head
424
innervation of tensor tympani
mandibular division of trigeminal
425
function of third division of trigeminal
tension on tympanic membrane
426
innervation of lacrimal glands
facial
427
innervation of submandibular, sublingual and parotid
maxillary division of trigeminal
428
what passes through cavernous sinus?
O TOM CAT
oculomotor
trochlear
ophthalmic trigeminal
maxillary trigeminal
internal carotid
abducens
429
function of cornea
transmission of light
refraction
430
structure and function of sclera
white capsule around the eye except anterior surface where it is cornea
protection
continuation of dura and cornea
431
middle layer of eye
uvea
432
iris
specialised section of choroid
controls pupil size
sphincter muscles make pupil smaller
dilator muscles make pupil larger
give eye colour
433
ciliary body
smooth muscle control accommodation
innervated by PNS
glandular epithelium - produces aqueous humour
behind iris
434
where is the pars plana?
iris sclera junction
435
choroid
nutrition of the outer retina
heat sink
darkly pigmented to absorb stray photons
highly vascular
436
where is vitreous humour produced?
retina
437
where is light focused onto in the retina?
fovea centralis
this is in the middle of the macula lutea
438
what does the macula lutea have a high concentration of?
cones
439
where are the photoreceptors?
retinal pigment epithelium
440
function of rods
dim lighting, peripheral vision
441
function of cones
colour vision
442
layers of tear film, source and function
anterior - lipid from meibomiun gland - prevent evaporation
middle - aqueous from lacrimal glands - prevents infection
posterior - mucus from goblet cells - hydrophilic, even distribution of tear film
443
aqueous humour
produced by ciliary epithelium in ciliary body
maintains intraocular pressure
444
vitreous humour
collagen matrix
hyaluronic acid and water
445
what is intraocular prressure maintained at?
12-20mmHg
446
which parts of the eye refract light?
cornea and lens
447
photon pathway
tear film, cornea, aqueous humour, lens, vitreous humour, ganglion ceell, amacrine cell, bipolar cell, horizontal cell, cone, rods, pigmented epithelium (absorption of excess photons)
448
blood supply to the eye
internal carotid
- opthalamic artery, central retinal artery, ciliary arteries
external carotid
- facial artery supplies medial lid and orbit
449
in which bone is the optic canal?
sphenoid
450
extracranial visual pathway
optic nerve formed by convergence of axons from retinal ganglion cells
RGCs receive impulses from rods and cones
optic nerve leaves via optic canal
451
ntracranial visual pathway
optic chiasm in middle cranial fossa
nasal fibres cross
temporal fibres do not cross
optic tracts travel to lateral geniculate nucleus in the thalamus and fibres synapse
axons from LGN carry visula information via optic radiations
to visual cortex
452
Bauman's loops
fibres from superior retinal quadrant
this is the inferior visual field
parietal lobe
453
meyers loop
fibres from inferior retinal quadrant
this is the superior visual field
temporal lobe
454
intortion
internal rotation towards midline
455
extortion
external rotation away from midline
456
which ocular muscles are controlled by nervees other than oculomotor?
LR6SO4
457
damage to left optic nerve
left eye blindness
458
damage to optic chiasm
bitemporal hemianopia
459
damage to left optic tract
loss of temporal vision of left eye and nasal vision of right eye
460
damage to left Meyers loop
loss of superior nasal field of left eye and superior temporal field of right eye
stuff in upper right of eye diagrams pretty much
461
two pathways of the auditory system
lemniscal and non-lemniscal
462
organ of Corti
organ of the inner ear located within the cochlea which contributes to audition. The Organ of Corti includes three rows of outer hair cells and one row of inner hair cells.
463
which nerve carries information from the organ of corti?
vestibulocochlear
464
lemniscal pathway
carries auditory information to the primary auditory cortex
465
non-lemniscal pathway
unconscious perception
do not lead to primary auditory cortex
466
spiral ganglion
cell bodies of first order neurons located here
467
wherre does the spiral ganglion recieve information from?
organ of corti - hair cells
468
where do first order auditory neurons synapse?
ipsilateral cochlear nuclei
469
auditory pathway
spiral ganglion receives information from organ of corti
vestibulocochlear nevre enters via internal acoustic meatus
travels to brainstem
first order neurons synapse at the ipsilateral cochlear nuclei
fibres of cochlar nerve bifurcate
all fibres arrive at the inferior colliculus
fibres project to ipsilateral medial geniculate body in the thalamus
projections process to primay auditory complex in temporal lobe
organised tonotrophically
470
do non-lemniscal pathways lead to primary auditory cortex?
no
471
label the ear
.
472
pathway of venous drainage starting at the great cerebral vein
great cerebral vein, straight sinus, transverse sinus, sigmoid sinus, internal jugular vein, jugular vein, brachiocephalic vein (formed by uniting with subclavian), SVC
473
confluence of sinuses
straight sinus and superior saggital sinus
474
lining of ventricles
ependyma
475
what are vertebral arteries a branch of?
subclavian
476
upper border of thyroid cartilage
C4
477
whee does the common carotid bifurcate?
upper border of thyroid cartilage
C4
478
two other extraocular muscles innervated by CN3
levator palpebrae superioris
sphincter pupillae
479
motor innervation of stapedius
facial
480
which glands does the facial nerve innervate?
sublingual, submandibular, lacrimal
481
innervation and function of CN8
cochlea and vestibular apparatus
hearing and proprioception of the head
balance
482
sensory, motor and paraympathetic innervation of glossopharyngeal
sensory
- posterior third of tonguee
- middle ear
- pharynx
- carotid bodies
motor
- stylopharyngeus
parasympathetic
- parotid
483
what innervates carotid body?
glossopharyngeal
484
what innervates aortic body?
vagus
485
what nnervates external ear?
vagus
486
which nerve is responsible for swallowing and speech?
vagus
487
functions of glossopharyngeal
general sensation, tase, chemo/ baro reception, swallowing (motor), salivation
488
which region of the vertebrae rotates the most?
thoracic
489
which region has the least capacity for flexion?
thoracic
due to ribcage
490
components of intervertebral discs
inner nucleus pulposus
outer annulus fibrosus - collagen
491
what does the ligamentum flavum connect?
laminae of adjacent vertebrae
492
where does the spinal cord end in
an adult
birth
an embryo
L2
L3
runs entire length of vertebral column
493
where would you insert a lumbar puncture?
L3/L4 n subarachnoid space
494
where do the internal carotid arteries enter the skull?
carotid foramina
495
cauda equina
spinal nerves from lower spnal cord that hang obliquely downwards
496
dermatome
area of skin with a sensory nerve supply from a single root of the spinal cord
497
thumb dermatome
C6
498
knee dermatome
L3
499
biig toe dermatome
L5
500
4 ascending tracts
DCML
spinothalamic
spinocerebellar
spinoreticular
501
where is the 3rd ventricle formed in the embryo?
diencephalon
502
pluripotent stem cells within nural folds
neural crest cells
503
which vitamins ensure the neural tube fuses?
B9 - folic acid
B12
504
substances within CSF
protein
urea
glucose
salts
505
endorphins
peptides with opiate like effects
inhibit substance p release
506
how long does the refractory period last?
5-10ms
507
which meningeal layers are vascularised?
dura and pia
not arachnoid
508
does the function of a muscle affect how namy muscle fibres there are?
yes
fingertips have fewer fibres for greater resolution of movement
509
where are UMN cell bodies?
primary motor cortex
510
where are LMN cell bodies?
brain stem or spinal cord
511
where do the optic tracts terminate?
lateral geniculate body in the thalamus
512
which bones make up the ossicular chain?
malleus, incus and stapes
MIS
stapes is attached to oval window
513
smallest bone in the body
stapes
514
function of ossicles
transmit vibrations from tympanic membrane to oval window
515
which muscles change the stiffness of the ossicular chain?
stapedius and tensor tympani
516
innervation of stapedius
facial
517
innervation of tensor tympani
trigeminal
518
function of stapedius and tensor tympani
control the mobility of malleus and stapes
protect the inner ear from loud noises
519
two ear windows
oval and round
520
function of the round window
vibrates with opposite phase to vibrations entering the inner ear through the oval window
moves fluid in the cochlea which means that hair cells of the basilar membrane will be stimulated and audition occurs
521
function of the vestibular system
balance and spatial orientation
522
what are the vestibular apparatus?
otolithic organs - utricle and saccule
semicircular canals
523
what do semicircular canals detect?
angular acceleration
524
what do otolithic organs detct?
linear acceleration
changes in head position relative to gravity
525
where are vestibular hair cells?
utricle, saccule, 3 ampulla at the base of the semicircular canals
526
function of vestibular hair cells
detect changes in motion and position of the head
527
function of cochlea
sound
528
what do the semicircular ducts contain?
fluid
529
what do the semicircular canals empty into?
sac called the utricle
530
where are the sense organs for balance?
semicircular ducts and utricle
531
where is information from the semicircular ducts sent to?
CN8 then nuclei in the medulla
vestibular nuclei
