Basic Science Flashcards
(418 cards)
1
Q
What are the 5 morphological regions of a neuron?
A
dendrites soma axon hillock axon synapse
2
Q
what is the function of dendrites within a neuron?
A
increase surface area of neuron cell membrane and receives inputs from other neurones
3
Q
what is the function of the soma of a neuron?
A
integrates the input signal to generate a net depolarising or hyperpolarising signal
4
Q
how are the input signals entering a neuron passed from the dendrites to the soma to the axon hillock?
A
passively
5
Q
what is the function of the axon hillock?
A
site of initiation of all-or-none AP
6
Q
what are the 2 main types of pain?
A
nociceptive pain
neuropathic pain
7
Q
compare nociceptive and neuropathic pain?
A
nociceptive- an appropriate physiological response to painful stimuli via intact nervous system
neuropathic- an inappropriate response to caused by a dysfunction in the nervous system
8
Q
what is allodynia?
A
pain from a non-painful stimulus
9
Q
what is hyperalgesia?
A
more pain than expected from a painful stimulus
10
Q
what type of pain do NSAIDs mainly act on?
A
nociceptive pain
11
Q
what is the mode of action of NSAIDs?
A
inhibit COX
reduce prostaglandin synthesis
12
Q
what are the 3 main side effects of NSAIDs?
A
- GI irritation/bleeding
- renal toxicity
- cardiovascular side effects (COX 2)
13
Q
what effect does paracetamol have in addition to its analgesic effects?
A
antipyretic
14
Q
what is the mode of action of paracetamol?
A
inhibition of central prostaglandin synthesis
15
Q
what is the main side effect of paracetamol?
A
risk of liver damage
16
Q
what type of pain do opiods mainly act on?
A
nociceptive pain
17
Q
what is the mode of action of opiods?
A
activate the endogenous analgesic system
modulate pain perception
reduce pain signal transmission
18
Q
what are the 6 main side effects of opiods?
A
nausea vomiting constipation dizziness/vertigo drowsiness dry skin/pruritus
19
Q
what type of pain do tricyclic antidepressants mainly act on?
A
neuropathic pain
20
Q
what class of pain medication works best for complex regional pain syndrome?
A
tricyclic antidepressants
21
Q
what class of pain medication works best for tension headaches?
A
tricyclic antidepressants
22
Q
what are the 6 main side effects of tricyclic antidepressants?
A
constipation dry mouth drowsiness abnormalities in heart rate/rhythm insomnia increased appetite
23
Q
what type of pain do SNRI/SSRIs mainly act on?
A
neuropathic pain
24
Q
what is the mode of action of SNRI/SSRIs?
A
selectively inhibit reuptake of noradrenaline or serotonin
25
what are the 7 main side effects of SNRI/SSRIs?
```
nausea
vomiting
constipation
drowsiness
dry mouth
increased sweating
loss of appetite
```
26
what type of pain do anticonvulsants mainly act on?
neuropathic pain
27
what is the mode of action of gabapentin? (anticonvulsant)
binds to presynaptic voltage-dependent calcium channels
28
what is the mode of action of pregabalin? (anticonvulsant)
interacts with N-type calcium channels
29
what is the mode of action of carbamazepine? (anticonvulsant)
block Na and Ca channels
30
what pain fibres do topical analgesics work on?
A-delta fibres
| C-fibres
31
what are the main 3 side effects of topical analgesics?
rash
pruritus
erythema
32
what are the 6 main side effects of anti-convulsants?
```
sedation
dizziness
ataxia
peripheral oedema
nausea
weight gain
```
33
what is ataxia?
loss of full control of body movements
34
in a neuron what is the rough ER known as?
nissl substance
35
what is the function of an axon with a neuron?
conducts APs to other neurones
| mediates transport of materials between soma and presynaptic terminal
36
what are the 2 main ways of axoplasmi transport within a neuron?
anterograde
| retrograde
37
what are the 2 rates of axoplasmic transport?
fast
| slow
38
how does polio get into the soma of a neuron?
gets into presynaptic terminal and then via retrograde axoplasmic transport reaches the soma
39
what is a neurite of a neuron?
a process arising from the soma
40
what are the 4 main type of neuron?
unipolar
pseudounipolar
bipolar
multipolar
41
how many neurites does a unipolar neuron have?
1 neurite
42
how many neurites does a pseudounipolar neuron have?
1 neurite
43
how many neurites does a bipolar neuron have?
2 neurites
44
how many neurites does a multipolar neuron have?
3+ neurites
45
compare a unipolar neuron to a pseudounipolar neuron?
both have one neurite, but the pseudounipolar neurones neurite bifurcates into two axons
46
what is the normal resting membrane potential?
-70mV
47
what is the membrane potential threshold for voltage activated Na channels to open?
-60mV
48
in the upstroke of an AP in a neuron, what is the resting membrane potential?
+40mV
49
influx of what ion causes the upstroke in an AP?
influx of Na
50
efflux of what ion causes the dowstroke in an AP?
efflux of K
51
what does myelin do to the passive current spread of APs?
increases speed
52
what cells provide the myelin sheath in the PNS?
schwann cells
53
what cells provide the myelin sheath in the CNS?
oligodendrocytes
54
compare schwann cells and oligodendrocytes in how they insulate axons?
many schwann cells needed for one axon
| one oligodendrocyte surrounds many axons
55
what are nodes of ranvier?
gaps in the myelin sheath
56
what type of conduction occurs through the nodes of ranvier?
saltatory conduction
57
what type of cells are schwann cells and oligodendrocytes?
macroglia
58
does MS cause demyelination in the CNS or PNS?
CNS
59
does Guillian-Barre syndrome cause demyelination in the CNS or PNS?
PNS
60
what are the 3 main types of synapse?
axodendritic
axosomatic
axoaxonic
61
what is an axodendritic synapse?
synapse between an axon of one neuron and the dendrite of another
62
what is an axosomatic synapse?
synapse between an axon of one neuron and the soma of another
63
what is an axoaxonic synapse?
synapse between an aon of one neuron and the axon of another
64
what is the most common type of synapse?
axodendritic
65
how are synapses functionally classified?
inhibitory or excitatory
66
is an excitatory response depolarising or hyperpolarising?
depolarising
67
is an inhibitory response depolarising or hyperpolarising?
hyperpolarising
68
what is the main transmitter used in excitatory synapses in the CNS?
glutamate
69
what are the main transmitters used in the inhibitory synapses in the CNS?
GABA or glycine
70
what receptors does glutamate activate?
post-synaptic cation selective, ionotropic, glutamate receptors
71
what receptors do GABA or glucine activate?
post-synaptic anion selective, ionotropic GABA or glycine receptors
72
what are the major amino acid neurotransmitters in the CNS?
glutamate, GABA and glycine
73
what charge influx occurs when glutamate activates the cation selective, ionotropic glutamate receptors on the postsynaptic neuron? what does this cause?
positive influx
| depolarisation
74
what occurs when GABA or glycine activates the anion selective ionotropic GABA/glycine receptors on the postsynaptic neuron? what does this cause?
negative influx
| hyperpolarisation
75
what are pre and post synaptic membranes separated by?
synaptic cleft
76
what is spatial summation?
many inputs converge upon a neuron to determine its output
77
what is temporal summation?
output determined by the frequency of APs of a single input
78
compare the type of vesicles amino acids, amines and peptides are released from?
amino acids and amines- synaptic vesicles
| peptides- secretory vesicles
79
compare ionotropic ligand-gated ion channels and G-protein coupled receptors in terms of speed of neurotransmission?
ionotropic ligand gated ion channels- fast
| GPCR- slow
80
what causes the release of neurotransmitter from vesicles into the synaptic cleft?
influx of Ca through voltage gated Ca channels
81
after neurotransmitters activate receptors on the post-synaptic membrane, what are the 2 things that can happen to them?
1. enzyme-mediate inactivation of transmitter
| 2. reuptake of transmitter
82
compare glycine, glutamate, GABA and amines in terms of what cells make them?
glycine and glutamate- all cell
| GABA, amines- neurones specifically
83
how are enzymes that are synthesised in the cell body of neuron transported to the presynaptic terminal?
axoplasmic transport via microtubules
84
at resting membrane potential, describe the flow of Na, Ca, Cl and K if they were to move freely?
Na flows inward
Ca flows inward
Cl flows inward
K flows outward
85
do drugs that are agonists of Na channels cause excitation or inhibition of neurotransmission?
excitation
86
do drugs that are antagonists of Na channels cause excitation or inhibition of neurotransmission?
inhibition
87
do drugs that are agonist of K channels cause excitation or inhibition of neurotransmission?
inhibition
88
do drugs that are antagonists of K channels cause excitation or inhibition of neurotransmission?
excitation
89
compare ionotropic and metabotropic receptors?
ionotropic receptors are direct signalling- fast
| metanotropic receptors are indirect signalling- slow
90
what neurotransmitters signal via non-NMDA ionotropic receptors?
AMPA
| kainate
91
compare non-NMDA and NMDA in terms of what components within an excitatory synaptic potential they mediate?
non-NMDA- fast component
| NMDA- slow component
92
what are the 2 types of receptor GABA activates?
ionotropic GABAa receptor
| metabotropic GABAb receptor
93
what channel does the ionotropic GABAa receptor operate?
Cl-
94
what channel does the metabotropic GABAb receptor operate?
usually K+ channel
95
what do benzodiazepines do to the GABAa receptor?
```
positive modulator (allosterically)
therefore increase Cl- entry to enhance inhibition
```
96
what is a quanta?
amount of neurotransmitter released from a single vesicle
97
what are the 2 types of low threshold sensory units?
- low threshold mechanoreceptors
| - low threshold thermoreceptors
98
what are the 4 types of high threshold sensory units?
- high threshold mechanoreceptors (mechanical nociceptors)
- thermal nociceptors
- chemical nociceptors
- polymodal nociceptors
99
what do polymodal nociceptors respond to?
at least 2 of:
- high intenity mechanical stimuli
- extreme degrees of heat
- substances in tissue
100
what are the 4 types of axons arising from skin/muscle?
Aa/I
Ab/II
Ad/III
C/IV
101
as you move from axon group I to IV, what happens to myelination and conduction velocity?
degree of myelination decreases
| conduction velocity increases
102
what group of axons are involved in proprioception of skeletal muscles?
Aa/I
103
what group of axons are involved in temperature pain and itch?
C/IV
104
what group of axons are involved in pain and temperature?
Ad/III
105
what group of axons are involved in low intensity mechanical stimulation of skin?
Ab/II
106
how is the receptive field of a neurone measured?
two-point discrimination
107
what is the major difference between meissner's corpuscles and merkel's discs in terms of location on skin?
meissner's corpuscles are not present on hairy skin
| merkel's disc are
108
what is brown-sequard syndrome?
ipsilateral hemiplegia with contralateral pain and temperature deficits
109
when does the dorsal column medial leminscal pathway cross the spinal cord?
great sensory decussation in the brainstem
110
when does the spinothalmic tract cross the spinal cord?
at level of output from the spinal cord
111
what are the dorsal column medial leminscal pathways formed by?
fasciculus gracilis
| fasciculus cuneatus
112
which is more medial- fasciculus gracilis or fasciculus cuneatus?
fasciculus gracilis
113
compare sensory input to T6 and below with above T6
T6 and below- fasciculus gracilis
| above- fasciculus cuneatus
114
what is the major route by which touch and proprioceptive information ascends to the cerebral cortex?
dorsal column medial lemniscal pathway
115
what horn within the spinal cord do the first order neurones in the dorsal column medial lemniscal pathway enter?
dorsal horn
116
where do the first order neurones in the dorsal column medial lemniscal synapse?
dorsal column gracile nucleus and cuneate nucleus
117
once the second order neurones in the dorsal column medial lemniscal pathway cross at the great sensory decussation where do they ascend?
medial lemniscus
118
once the second order neurones in the dorsal column medial lemniscal pathway ascend the medial lemniscus, where do they synapse?
ventral posteriolateral nucleus of the thalamus
119
where do the third order neurones in the dorsal column medial lemniscal pathway synapse?
primary somatosensory cortex (S1)
120
what replaces the dorsal column medial lemniscal pathway in conveying sensory information from the anterior head?
trigeminal system
121
what is stereognosis?
ability to recognise an object by feeling it
122
what are the 5 main capabilities of the dorsal column medial lemniscal pathway?
```
stereognosis
vibration detection
fine touch
conscious proprioception
weight discrimination
```
123
what are the 3 divisions of the trigeminal nerve?
V1 ophthalmic
V2 maxillary
V3 mandibular
124
where do primary neurones in the trigeminal system synapse?
in chief sensory nucleus of spinal nucleus
125
where do secondary neurones in the trigeminal system synapse?
ventroposteriomedial nucleus of the thalamus
126
where do third order neurones in the trigeminal system synapse?
cortex
127
where is the somatosensory cortex located?
in the post central gyrus of the parietal cortex
128
where is the post central gyrus of the parietal cortex in relation to the central sulcus?
post central gyrus of the parietal cortex is immediately posterior to the parietal cortex
129
what are the 4 areas of the somatosensory cortex?
brodmann areas 1, 2, 3a, 3b
130
what percentages of input from the ventral posteriomedial go to the brodmann areas of the somatosensory cortex?
30% to BA 1 and 2
| 70% to BA 3a and 3b
131
where does the input for brodmann area 1 come from?
cutaneous input
132
where does the input for brodmann area 2 come from?
joint afferents, golgi tendon organs, deep tissues
133
where does the input for brodmann area 3a come from?
proprioreceptors (muscle spindles)
134
where does the input for brodmann area 3b come from?
cutaneous receptors
135
what does brodmann area 1 sense?
texture discrimination
136
what does brodmann area 2 sense?
object perception (ie sterognosis)
137
what does brodmann area 3a sense?
body position
138
what does brodmann area 3b sense?
touch
139
how many layers are within the somatosensory cortex?
six cell layers
140
thalamic inputs to the somatosentsory cortex terminate mainly on neurnes within which layer?
layer IV
141
if an area of the body is amputed, what happens to the area of somatosensory cortex representing the finger?
utilised by other sensoryy inputs
142
what happens to the area of somatosensory cortex representing an area of the body that has a lot of sensory activity?
slowly increases relatively
143
what do alpha motor neurones innervate?
a bulk of muscle fibres within a muscle
144
what do gamma motor neurones innervate?
muscle spindle fibres
145
axons of lower motor neurones leave the spinal cord from which spinal roots?
ventral roots
146
ventral roots join dorsal roots to form what nerves?
mixed spinal nerves
147
what type of nerve fibres do mixed spinal nerves consist of?
sensory and motor fibres
148
what are the 2 enlargements of motor neurone bundles within the spinal cord?
cervical enlargment
| lumbar enlargement
149
what does the cervical enlargement of motor neurones supply?
the arm
150
what does the lumbar enlargement of motor neurones supply?
the leg
151
what is the smallest functional component of the motor system?
motor unit
152
what does a motor unit consist of?
alpha motor neurone and all of the skeletal muscle fibres that it innervates
153
what is the name for a collection of alpha motor neurones that innervate a single muscle?
motor neurone pool
154
what are the 2 principles that grades the force of muscle contraction?
- frequency of APs from the alpha motor neuron
| - recruitement of additional synergistic motor units
155
within the ventral horn, where are LMNs innervating axial muscles in relation to LMNs innervating distal muscles?
LMNs innervating axial muscles are medial to those innervating distal muscles
156
within the ventral horn, where are the LMNs innervating flexors in relation to LMNs innervating extensors?
LMNs innervating flexors are dorsal to those innervating extensors
157
compare unfused tetani to fused tetani?
unfused tetani- time for muscle relaxation between contractions
fused tetani- no time for relaxation between contractions
158
compare the soma diameters of the alpha motor neurones of small motor units compared with larger motor units?
the smaller the motor uni the smaller the soma of the alpha motor unit
159
what are the main 2 classes of skeletal muscle fibres?
```
slow oxidative (type 1)
fast fibres (type 2)
```
160
what are the 2 types of fast skeletal muscle fibres?
type 2a
| type 2b
161
how is ATP derived in type 1 skeletal muscle fibres?
oxidative phosphorylation
162
how is ATP derived in type 2a skeletal muscle fibres?
oxidative phosphorylation
163
how is ATP derived in type 2b skeletal muscle fibres?
from glycolysis
164
why are type 1 skeletal muscles red in colour?
high myoglobin content
165
compare speed of contraction of type 1, 2a and 2b skeletal muscles fibres?
1- slow
| 2a and 2b- fast
166
compare type 1, 2a and 2b skeletal muscles in the ability to fatigue?
1- fatigue resistant
2a- fatigue resistant
2b- not fatigue resistant
167
what are the 3 types of motor units?
slow
fatigue resistant
fast fatiguing
168
compare type 1, 2a and 2b skeletal muscles in terms of size of alpha motor neuron?
1- small a-MN
2a- intermediate a-MN
2b- large
169
what happens to the AP threshold as the size of the alpha-motor neuron increases? (Henneman Size Principle)
AP threshold increases
170
what is the myotatic reflex?
when a muscle is stretched, it contracts
171
what sensory organ registers change in length of a muscle?
muscle spindle fibre
172
compare intrafusal and extrafusal muscle fibres in terms of ability to generate muscle force?
intrafusal- don't generate force
| extrafusal- generate force
173
what type of reflex arc is the myotatic reflex?
monosynaptic reflex arc
174
what neurotransmitter mediates the myotatic reflex?
release of glutamate (excitatory)
175
what spinal cord level is tested by the supinator reflex?
C5/6
176
what spinal cord level is tested by the biceps reflex?
C5/6
177
what spinal cord level is tested by the triceps reflex?
C7
178
what spinal cord level is tested by the quadriceps reflex?
L3/4
179
what spinal cord level is tested by the gastrocnemius reflex?
S1
180
during voluntatry movement, why are a-MN and y-MN normally co-activated?
so that the intrafusal muscle fibres contract in parallel with the extrafusal fibres, stops spindle going slack and therefore maintains sensitivity
181
where are golgi tendon organs located?
at junction of muscle and tendon
182
what is the function of golgi tendon organs?
regulate muscle tension to protect from overload
183
what is the inverse myotactic reflex?
contraction of skeletal muscle causes muscle to relax
184
what are the components of the inverse myotactic reflex?
-Ib afferent nerve which innervates golgi tendon organ
and synapses inhibitory interneurone
which causes alpha motor neurone to relax
185
where are the 3 main organs/cells/receptors that proprioceptive information arises from?
- muscle spindles
- golgi tendon organs
- joint receptors
186
what type of interneurons mediate the inverse myotatic response?
inhibitory interneurons
187
what type of interneurones mediate reciprocal inhibition between extensor and flexor muscles?
inhibitory interneurons
188
what type of interneurons mediate the flexor reflex?
excitatory interneurons and inhibitory interneurons
189
what is the flexor reflex?
when a limb flexes in response to noxious stimuli
190
what type of interneurons mediate the crossed extensor reflex?
excitatory interneurons and inhibitory interneurons
191
what is the crossed extensor reflex?
during flexor reflex, the contralateral limb extends in order to maintain balance
192
what are the 2 important descending spinal tracts?
lateral spinal tracts
| ventromedial (/anteromedial) spinal tracts
193
what part of the brain are the lateral descending spinal tracts under control of?
cerebral cortex
194
what part of the brain are the venteromedial descending spinal tracts under control of?
brainstem
195
what is the function of the lateral descending spinal tracts?
voluntary control of distal muscles, eg for small skilled movements
196
what is the function of the ventromedial descending spinal tracts?
posture and locomotion
197
what is the major lateral descending spinal tract?
the corticospinal (or pyramidal) tract
198
where do the fibres from the corticospinal tract cross?
85% cross in the medulla
| 15% cross at level of exit
199
for the fibres of the corticospinal tract which cross at the medulla, what is this tract now named?
lateral corticospinal tract
200
for the fibres of the corticospinal tract which dont cross at the medulla, what is this tract now named?
ventral corticospinal tract
201
compare how far axons from the lateral vestibular nucleus and the medial vestibular nucleus travel down the spinal cord?
lateral -down to lumbar spinal cord
| medial - down to cervical spinal cord
202
what is the function of the lateral vestibulospinal tract?
helps hold body upright by facilitating antigravity muscles
203
what is the function of the medial vestibulospinal tract?
head movements
204
compare skin, muscle and viscera in terms of how localised pain is?
skin- well localised
muscle- poorly localised
viscera- poorly localised
205
what are nociceptors activated by?
intense noxious or damaging stimuli
206
where are nociceptor cell bodies located?
dorsal root ganglia or trigeminal ganglia
207
what order neurones are nociceptors?
first order neurones
208
what sensory fibres do nociceptors comprise of?
Ad and C fibres
209
what kind of noxious stimuli do Ad fibres respond to?
noxious mechanical and thermal stimuli
210
what kind of noxious stimuli do C fibres respond to?
all noxious stimuli (polymodal)
211
compare Ad and C fibres response time to noxious stimuli?
Ad- fast
| C- slow
212
where are soma of trigeminal sensory neurones located?
trigeminal sensory ganglion
213
the second order neurones of the trigeminal system project to the ventroposteriomedial nucleus of the thalamus via what?
trigeminal lemniscus
214
the third order neurones of the trigeminal system project to the cortex via what?
thalamocortical neurones
215
what is CT contrast determined by?
electron density
216
what artificial contrast agents can be used on CT scan?
injected iodine based agents
217
why do iodine based agents not pass into the brain?
because of the blood brain barrier
218
if iodine based contrast agents cannot get into the brain, why are they used in brain CT?
because if there is enhancement (whiteness) it shows that the blood brain barrier has been disrupted (some pathology)
219
how long after a CT angiogram will the CT venogram occur?
30 seconds
220
what is MRI contrast deterined by?
Proton density, T1 and T2
221
what artificial contrast material can be used in T1 weighted MRI?
injected gadolinium compounds
222
compare bone detail of CT and MRI?
CT has better bone detail
223
which is generally more tolerated by patients- CT or MRI?
CT
224
what is the most common cause of spontaneous subarachnoid haemorrhage?
ruptured aneurysm
225
what investigation is needed to rule out a subarachnoid haemorrhage if CT scan is negative?
lumbar puncture
226
what are the 2 main methods of aneurysm treatment?
craniotomy and clipping of aneurysm
| endovascular treatment
227
which form of imaging (CT or MRI) is compatible with most ICU/emergency equipment?
CT
228
what type of inheritance is duchennes muscular dystrophy?
X-linked recessive
229
what type of inheritance is huntingtons disease?
autosomal dominant
230
what area of childhood development is delayed in duchennes muscular dystrophy?
delay in motor development
231
at what age does the weakness of muscle start in duchennes muscular dystrophy?
3-4 years
232
why do patients with duchennes muscular dystrophy die in their 20s?
death from involvement of respiratory and cardiac muscles
233
in both duchennes and beckers muscular dystrophy, what happens to the calves?
calf hypertrophy
234
what gene is affected in duchennes muscular dystrophy?
dystrophin gene
235
what marker is very raised in muscular dystrophys?
serum creatinine kinase
236
what is dystonia?
abnormal muscle tone
237
what is the genetic defect in huntingtons disease?
repeated CAG codes (codes for glutamine)
238
what is the most common cause of dementia?
alzheimers
239
what are the 3 main pathologies within the brain that lead to alzheimer disease?
- loss of cortical neurones
- neurofibrillary tangles (intracellular)
- senile plaques (Extracellular)
240
what are the senile plaques in alzheimers made of?
amyloid B protein
241
amyloid B protein is a fragment of the product of what protein?
amyloid precursor protein
242
what chromosome is the gene for amyloid precursor protein?
chromosome 21
243
what apolipoprotein allele predisposes to alzheimers disease?
apolipoprotein E4
244
what are the 2 distinct processes of sensitisation of the nociceptive pathway following tissue damage?
peripheral sensitisation
| central sensitisation
245
does peripheral sensitisation after tissue damage cause primary or secondary hyperalgesia?
primary hyperalgesia
246
does central sensitisation after tissue damage cause primary or secondary hyperalgesia?
secondary hyperalgesia
247
which causes allodynia after tissue damage- peripheral or central sensitisation?
central sensitisation
248
which type of pain sensitisation is the cause of persistant pain after tissue healing?
central sensitisation
249
what are the 2 nociceptive tracts?
spinothalmic tract
| spinoreticular tract
250
where in the spinal column are the nociceptive tracts?
anterolateral spinal cord
251
within the dorsal horn of the spinal cord, sensory primary afferent nerves terminate at what?
the laminae of rexed (I- V)
252
what is located in the dorsal root ganglia?
cell bodies of primary afferent sensory neurones
253
in which lamina of rexed do nociceptive C fibres terminate?
laminae I and II
254
in which lamina of rexed do nociceptive Ae terminate?
laminae I, II and V
255
what type of pain does the spinoreticular tract mainly transmit?
slow C-fibre pain
256
what type of pain does the spinothalmic tract mainly transmit?
fast fibre pain
257
where do second order neurones of the spinothalmic tract terminate?
posterior and ventroposterior thalamus
258
where do second order neurones of the spinoreticular tract terminate?
reticular nuclei in the brainstem
259
within the spinothalmic tract, what neurones relay the signal from the thalamus to the primary somatosensory cortex?
thalamocortical neurones
260
within the spinoreticular tract, what neurones relay the signal from the reticular formation to the thalamus?
reticulothalamic tracts
261
within the spinoreticular tract, what neurones relay the signal from the thalamus to the limbic areas of the forebrain?
thalamocortical neurones
262
why does 'rubbing it better' actually help with pain?
counter-stimulation analgesia
-stimulation of non-nociceptive afferents activates inhibitory interneurones that suppress firing of the nociceptive pathway
263
how do TENS machines work?
counter-stimulation analgesia
-stimulation of non-nociceptive afferents activate inhibitory interneurones that suppress firing of the nociceptive pain pathway
264
how do NSAID reduce nociception?
act at site of injury to decrease nociception sensitisation in inflammation
265
how do local anaesthetics reduce nociception?
block nerve conduction
266
how do opiods reduce nociception?
modify transmission of nociceptive signals in the dorsal horn of the spinal cord and activating descending inhibitory controls
267
what is step 1 of the WHO analgesic ladder?
paracetamol or NSAID
268
what is step 2 of the WHO analgesic ladder?
NSAID + weak opiod
269
what is step 3 of the WHO analgesic ladder?
NSAID + strong opiod
270
what receptors mediate opiod action?
G protein coupled opiod receptors
271
what 2 things occur when opiods bind to G protein coupled opiod receptors?
- inhibition of voltage-activated Ca channels on presynaptic neurone (suppresses neurotransmitter release from nociceptor terminal)
- opening of K channels on postsynaptic neurone (hyperpolarises cell so suppresses neurone excitation)
272
what medical condition should you avoid tramadol in?
patients with epilepsy
273
what drugs can be used to reverse opiod toxicity?
```
naloxone
naltrexone (longer half life)
```
274
are aspirin, ibuprofen, naproxen, diclofenac and indometacin COX2-selective inhibitors or non selective inhibitors?
non-selective
275
what does inhibiting COX 1/2 do to rate of prostaglandin synthesis?
decreases synthesis
276
what specific prostaglandin is involed in sensitisation of nociceptive neurones?
PGE2
277
does inhibition of COX1 or COX2 cause GI toxicity?
inhibition of COX 1
278
what anti-convulsant drug is often used in painful diabetic neuropathy?
pregabalin
279
what anti-convulsant drug is used in migraine prophylaxis?
gabapentin
280
how do tricyclic antidepressants work?
act centrally by decreasing reuptake of noradrenaline
281
what drug is first line treatment in controlling trigeminal neuralgia?
carbamazepine
282
what is the function of the nodes of ranvier?
increases conduction speed
283
why are neurones particularly suscpetible to hypoxia?
cannot generate energy through anaebolic glycolysis
284
what are the 4 main neuronal responses to injury/disease?
acute neuronal injury
simple neuronal atrophy
sub-cellular alterations
axonal reaction
285
what is an axonal reaction?
a reaction within the cell body that is associated with axonal injury
286
why does the cell body of a neurone swell and the nucleus become peripherally displaced in response to axonal injury?
increased RNA and protein synthesis
287
in response to axonal injury, what way does the degeneration of the axon occur?
anterograde degeneration of axon distal to site of injury
288
what happens to the myelin sheath in response to axonal injury?
breakdown
289
what happens to the number of astrocytes in response to neuronal injury?
increases
290
what is gliosis?
proliferation of astrocytes as a reactive response to injury
291
what is the most important histopathological indicator of CNS damage?
gliosis
292
why do microglia proliferate in response to injury?
to phagocytose the debris of dying neurones (neuronphagia)
293
what are the two organs which autoregulate their blood supply?
brain and kidneys
294
above and below what BP, are the brain/kidneys unable to regulate their blood flow?
below DBP 50mmHg
| above DBP 130mmHg
295
within the brain, what happens to the vasculature in response to hypotension?
dilates to maintain blood flow
296
within the brain, what happens to the vasculature in response to hypertension?
constricts to maintain blood flow
297
what lobe is affected in an anterior cerebral artery stroke?
frontal lobe
298
what is aphasia/dysphasia?
language disorder
299
in a middle cerebral artery stoke, what is an important determinant of how bad the signs/symptoms will be?
if dominant or non-dominant side is affected
300
why are brainstem infarcts life threatening?
because cardiorespiratory centres might be affected
301
what part of the brain is affected in webers syndrome?
midbrain
302
what part of the brain is affected in medial and lateral inferior pontine syndromes?
pons
303
what part of the brain is affected in lateral medullary syndrome?
medulla
304
what visual field defect can occur with an infarct causing damage to the occipital lobe?
homonymous hemianopia with macular sparing
305
what kind of gait is acquired in a infarct affecting the cerebellum?
ataxic gait
306
what is an intention tremor?
a tremor which is not present at rest but is worse as you are trying to do something
307
what are watershed areas within the brain?
boundary areas of where the cerebral arteries meet
308
when do watershed infarcts occur?
fall in blood pressure
309
what lobe of the cerebrum is affected by a posterior cerebral artery infarct?
occipital
310
why do haemorrhages within the brain cause ischaemia?
- blood vessel goes into spasm
| - can act like a SOL causing increased ICP resulting in impaired blood flow to the brain
311
what is the strongest risk factor for a stroke caused by cerebral haemorrhage?
hypertension
312
what are arteriovenous malformations?
failure in normal development of an artery leading to high pressures within the vein
-suscpetible to tearing
313
in mild and moderate ischaemia to the brain, what cells are first to be lost?
neurones
314
what is a stroke?
sudden disturbance of cerebral function of vascular origin that causes death or lasts over 24 hours
315
what is a TIA?
sudden disturbance in cerebral function which lasts less than 24 hours
316
which is more common- stroke due to infarction or haemorrhage?
infarction
317
what are the 2 most common originating sites for an embolism causing stroke?
heart and carotid arteries
318
which cerebral arteries are most likely to be affected by embolic strokes?
middle cerebral arteries
319
what are the 2 main complications of atheroma?
thrombosis
| aneurysm formation
320
why do cystic fluid filled spaces form as a consequence of cerebral infarct?
as cells die, the liquid phospholipids get left behind- this leaves fluid filled cysts
321
what is the most common cause of a spontaneous subarachnoid haemorrhage?
rupture of saccular/berry aneurysm
322
where do most saccular/berry aneurysms occur?
arterial bifurcations at internal carotid artery
323
what life saving procedure can be done for a saccular aneurysm?
clipping
324
what is the onset like for a subarachnoid haemorrhage?
abrupt
325
what are lacunes/lacunar infarcts?
small cavities found in the basal ganglia, thalamus and pons
326
who are lacunes/lacunar infarcts found in?
elderly patients or hypertensives (mainly)
327
when can hypertensive encephalopathy occur?
when severe hypertension exceeds the upper limit of autoregulation
328
what kind of dementia is associated with hypertension?
multi-infarct dementia
| accumulation of lacunar infarcts
329
what demyelinating condition can you get post measles?
subacute sclerosing panencephalitis
330
does MS affect white or grey matter?
white matter
331
what can you see on a cut-section of the brain of a patient with MS?
plaques
| areas of demyelination
332
describe the plaques of acute MS?
yellow/brown with an ill-defined edge
333
describe the plaques of chronic MS?
grey/brown and well demarcated
334
why is there an increased incidence of dementia in Downs syndrome?
because the genes involved are on chromosome 21 (downs is trisomy 21)
335
what lobe is generally spared of atrophy in Alzheimers?
occipital lobe
336
what do you see when staining amyloid with congo red and then looking at it under polarised light?
apple green birefringence
337
what protein is very commonly found in traumatic dementia especially?
tau protein
338
what are the hallmarks of dementia with Lewy bodies?
hallucinations and fluctuating levels of attention
339
what is the pathogenesis of dementia with lewy bodies?
degeneration of the substantia nigra
lewy bodies found in remaining nerve cells
cortical atrophy
340
what is the age of Huntingtons disease onset?
35-50 years old
341
what is the inheritance pattern of huntingtons disease?
autosomal dominant
342
what gene is involved in huntingtons disease?
huntingtin gene
343
what is the triad of clinical features for huntingtons disease?
emotional, cognitive and motor disturbance
344
what is myoclonus?
jerky contraction of groups of muscles
345
at what age is the onset of Pick's disease?
50-60 years old
346
in Picks disease, what is the frontal lobe function that has very prominent deterioration?
personality and social
347
what lobes are mainy affected in Pick's disease?
frontal and temporal lobes
348
what are the histological hallmarks of Pick's disease?
pick's cells (swollen neurones)
| pick's bodies (intracytoplasmic filamentous inclusions)
349
compare the progression of alzheimers and vascular dementia?
alzheimers is continuously progressive
| vascular dementia has an abrupt onset with stepwise progression
350
how do the ossicles within th emiddle ear correct for the loss of amplitude that occurs within the fluid in the cochlea?
impedance matching
| by increasing sound pressure (to match the loss that occurs later)
351
what are the 3 mechanisms by which the ossicles of the middle ear impedance match? (ie increase dBs)
- ratio of tympanic membrane to stapes footplate (20:1)
- lever action of ossicles
- buckling of tympanic membrane
352
what membrane separates the scala vestibuli from the scala media?
reissner's membrane
353
what membrane separates the scala media from the scala tympani?
basilar membrane
354
where does transduction occur in the inner ear?
organ of corti
355
where do the scala vestibuli and the scala tympani connect?
at helicotrema
356
what window does the scala vestibuli meet?
oval window
357
what window does the scala tympani meet?
round window
358
as the basilar membrane goes along (and increases in width), what frequency sound waves correspond to it?
decreasing frequency of sound waves
359
which auditory receptor hair cells are most abundant- inner or outer hair cells?
outer hair cells
360
what separates the inner and outer hair cells?
rods of corti
361
what are inner and outer hair cells?
auditory receptors with sterocilia
362
which two membranes within the inner ear do the hair cells stretch between?
basilar membrane and tectorial membrane
363
is the kinocilium directly before or after the stereocilia on a hair cell?
directly after
364
how does hair cell transduction occur? (ie how is an AP formed?)
force towards the kinocilium opens cation channels
K+ enters causing depolarisation
force then goes back away from the kinocilium
cation channels close
repolarisation
365
the bending of the hair cells in the cochlea causes vibration of which membrane?
tectorial membrane
366
which cells within the cochlea release neurotransmitter?
hair cells
367
compare inner and outer hair cells in terms of which sends afferent signals and which receives efferent signals?
inner hair cells- send afferent signals to auditory nerve
| outer hair cells- receive efferent signals
368
the efferent signals that outer hair cells receive control what?
stiffness
| to amplify membrane vibration
369
compare inner and outer hair cells in terms of the how many hair cells are innervated by a single nerve?
inner hair cells- one cell innervates many nerves
| outer hair cells- many nerves innervate one hair cell
370
what is the motor protein within the outer hair cells composed of?
prestin
371
what is the function of the motor protein within outer hair cells?
changes the length of the outer hair cells
372
why is it important that the outer hair cells change in length?
increased vibration of basilar membrane so increased bending of inner hair cells
373
why can furosemide cause hearing problems?
inactivates the membrane motor within the outer hair cells
374
does place code or temporal code operate for pitches under 5kHz?
temporal code for under 5kHz
375
does place code or temporal code operate for pitches above 5kHz?
place code
376
from cochlea to the auditory cortex, what the is central auditory pathway?
eight cranial nerve
```
cochlear nucleus
superior olivary complex
lateral lemniscus
inferior colliculus
medial geniculate body
```
377
where do sound waves from both ears merge?
superior olivary complex
378
what are the 3 cochlear nuclei?
dorsal cochlear nucleus
posteroventral cochlear nucleus
anteroventral cochlear nucleus
379
what part of the vestibular system senses head rotation?
semicircular canals
380
what part of the vestibular system senses translational motion and gravity?
saccule and utricle
381
within the semicircular canals, what do the cilia project into?
cupula
382
are the semicircular canals filled with endolymph or perilymph?
endolymph
383
what is the name for sheets of cells where hair cells are clustered within the semicircular canals?
crista
384
what plane does the saccule sense movement in?
verticle plane
385
what plane does the utricle sense movement in?
horizontal plane
386
what separates the hair cells within the otolith organs?
striola
387
compare the direction of hair cells in semicircular canals and otolith organs?
semicircular canals- all in same direction
| otolith organs- oriented in all directions
388
what are the 3 major vestibular reflexes?
vestibulo-ocular reflex
vestibulo-colic reflex
vestibular-spinal reflex
389
what is the vestibulo-ocular reflex?
keeps eyes wtill in space when head moves
390
what is the vestibulo-colic reflex?
keeps head still in space when you walk
391
what is the vestibular-spinal reflex?
adjusts for posture for rapid changes in position
392
why does alcohol cause dizziness?
makes the cupula less dense meaning it floats in the endolymph more
-you think you are rotating when you are still
393
what happens to the membrane potential of a photoreceptor when light enters the eye?
hyperpolarises
394
why do photoreceptors hyperpolarise when light enters the eye?
Na+ channels close
395
what does light do to 11-cis-retinal within rods?
converts it to its active form: all-trans-retinal
396
why do Na+ channels within photoreceptors cose when light enters the eye?
the all-trans-retinal that is formed causes the Na+ channels to close (and then cell hyperpolarises)
397
during phototransduction, compare light and dark in terms of how much glutamate there is?
light- less glutamate
| dark- more glutamate
398
what is visual acuity determined by?
photoreceptor spacing mainly
| and refractive power
399
what is the receptive field of a ganglion cell?
the part of the retina that needs to be stimulated to elicit APs from that specific ganglion cell
400
are rods or cnes used for seeing in dim light?
rods
401
do the ganglion cells of rods have high or low convergence?
high convergence
402
ganglion cells of rods have high convergence, what does this mean in terms of sensitivity and acuity?
increased sensitivity
| decreased acuity
403
do ganglion cells of cones have high or low convergence?
low convergence
404
ganglion cells of cones have low convergence, what does this mean in terms of sensitivity and acuity?
low sensitivity
| high acuity
405
as you move from blue to green to red light, what happens to the wavelength and the frequency?
wavelength increases
| frequency decreases
406
compare rods and cones in terms of chromaticity?
rods- achromatic
| cones- chromatic
407
compare rods and cones interms of location on the retina?
rods- peripheral
| cones- central
408
compare rods and cones in terms of light sensitivity?
rods- high light sensitivity
| cones- low light sensitivity
409
compare rods and cones in terms of visual acuity?
rods- low visual acuity
| cones- high visual acuity
410
lateral inhibition of neurones within the optic system aids with what?
localisation of image
411
what is the name for the synapse between the motor neuron and the muscle?
mtor end plate
412
what enzyme degrades acetylcholine?
acetylcholinesterase
413
what does acetylcholinesterase convert acetyl choline into?
acetate and choline
414
how does the curare (D-tubocuracine) poison kill you?
binds to the ACh receptor on the postysynaptic membrane and inhibits it
-no muscle contraction and so respiration stops
415
what are type 1 muscle fibres?
slow oxidative, resist fatigue
416
what are type 2a muscle fibres?
fast oxidative (aerobic)
417
what are type 2b muscle fibres?
fast glycolytic, easiy fatigued
418
what does a fasciculation usually indicate?
disease of motor neurone
