Physiology Flashcards
1
Q
What is neuropathic pain?
A
Nerve damage causing pain
2
Q
What is spontaneous pain?
A
Pain in the absence of a stimulus
3
Q
Two Major types of pain fibres and their properties?
A
A fibres - Fast, myelinated
C Fibres - Slow unmyelinated
4
Q
What type of pain are C fibres involved in transmitting?
A
Aching, burning pain
5
Q
What type of pain are A fibres involved in transmitting? the four types of fibre?
A
A alpha fibres - muscle pain
A beta fibres - mechanical
A gamma fibres - muscle and pressure
A delta - sharp pain
6
Q
What do substance P and CGRP do at peripheral synapses?
A
Lead to flare and oedema
7
Q
The two types of ascending pathways that transmit pain in the peripheries, their properties?
A
Spinothalamic (neospinothalamic)
- Direct
- immediate, exact location
Spinoreticulothalamic (Paleospinothalamic)
- Indirect
- Involve limbic structures (amygdala included)
- Emotional and visceral pain
- descending suppression of pain
8
Q
What fibres are involved in descending suppression of pain? What do they release?
A
C Fibres release glutamate and substance P
9
Q
How do glial cells respond to painful stimuli?
What can this lead to?
A
They release mediators to sensitise the post-synaptic receptor e.g.
IL 1 and 2 TNF NO Prostaglandins Glutamate ATP
This can lead to central sensitisation
10
Q
Two types of sensitisation?
A
Central
Peripheral
11
Q
What mostly leads to central sensitisation?
A
Repetitive input
12
Q
What does repetitive input produce?
A
Wind-up
13
Q
What is wind up?
A
Increased electrical activity that results in increased excitability of second order neurones in the spinal cord
14
Q
What two things can central sensitisation cause?
Define them
A
Allodynia - Pain from a stimulus that is not usually painful
Hyperalgesia - increased sensitivity to painful stimuli
15
Q
What are the three main mechanisms of central sensitisation?
A
Increase of membrane excitability
Synaptic facilitation
Disinhibition (less inhibitory neurotransmitters)
16
Q
Where does central modulation occur?
A
The dorsal horn
17
Q
One main example of how central modulation works?
A
The gate theory
18
Q
What is the gate theory?
A
the theory that descending pathways inhibit pain fibres
A beta fibres inhibit pain fibres in the dorsal horn
19
Q
Two main types of synapses in the CNS?
A
Electrical and chemical
20
Q
What type of synapses are gap junctions?
A
Electrical
21
Q
What type of synapses involve the SNARE complex?
A
Chemical
22
Q
What is the SNARE complex?
A
A complex in the pre-synaptic cell that changes in the presence of high intracellular calcium.
In the presence of high calcium the SNARE complex allows a pore to be formed between the vesicles and the cell membrane which allows neurotransmittors to be released.
23
Q
Three types of chemical synapse?
A
Axo-dendritic
Axo-somatic
Axo-axonic
24
Q
What is the one type of chemical synapse that is excitatory as well as inhibitory, also the most common by far?
A
Axo-dendritic
25
What is the speed of ionotropic receptors compared to metabotropic receptors?
Ionotropic - Fast
Metabotropic - Slow
26
Two main ways neuronal transmission is modulated?
G-protein coupled receptors (through second messengers)
Co-transmitters - excitatory and inhibitory (neuropeptides)
27
How do neuropeptides (co-transmitters) modulate neuronal activity?
Through their action on G-protein coupled receptors
They are only released in high Ca concentration
28
An example of a neuropeptide involved in pain? what does it do?
Substance P, increases pain transmission
29
What does enkephalin do?
Reduces pain through reduction of substance P and Glutamate
30
As each synapse releases on average 1 vesicle each (there are 10,000+) What are the two types of synaptic integration (summation)?
Temporal - summation at the same synapse
Spatial - from several different synapses
31
What is the loss of both temporal fields of the eye called?
Bitemporal hemianopsia
32
What area is damaged to cause bitemporal hemianopsia, example of what can cause this damage?
Optic chiasm
Pituitary tumour
33
Where would damage have occured to cause loss of vision in one eye? examples?
optic nerve
MS
Glioma
Head trauma
34
What artery would be damage to give one eye full vision loss
Anterior cerebral artery
35
Haemorrhage of what artery would cause bitemporal hemianopsia?
Anterior cerebral artery (anterior communicating artery)
36
What would loss of vision to the left temporal visual field and the right nasal field be called?
Left homonymous hemianopsia
37
Where would damage have occurred to cause left homonymous hemianopsia? Causes?
Optic tract (right side) OR optic radiations
Tumour
38
What artery would be damaged to cause left homonymous hemianopsia?
Posterior Cerebral Artery
39
What is left superior quadrantopsia? Causes?
Both superior left quadrants damaged
Temporal lobe tumour
40
Where is damaged to cause left superior quadrantopsia?
Meyers loop (the lower radiations)
41
What artery would be damaged to cause left superior quadrantopsia?
PCA
42
What are the two pathways from V1 (primary visual area)?
| What do they do?
The dorsal (parietal pathway) = movement
The ventral (temporal pathway) = colour and form
43
4 main conditions that give rise to acute neuro-dengeneration?
Traumatic brain injury
Stroke
TIA
Intracranial haemorrhage
44
Two types of stroke, which is more common?
Ischaemic (85%)
Haemorrhagic
45
Causes of an ischaemic stroke?
Occlusion e.g. atherosclerotic arteries
Emboli
46
Three main molecular mechanisms that lead to ischaemic neuro-degeneration?
Increased [Ca2+]
Increased Glutamate
Increased free radical levels
47
What's ischaemic depolarisation?
Large amounts of ATP are usually required to maintain resting potential (Na+/K+ pump)
In ischaemia there is no available ATP and depolarisation followed by normalisation of that resting potential occurs
48
What free radicals are produced in ischaemic neuro-degeneration and where?
Superoxide formed in mitochondria (O2-)
NO formed from arginine
Bind together to form ONOO-
49
How does raised calcium cause cell death in acute neuro-degeration?
Increased Free radical production
Oedema
activates proteases
50
Two classified areas of the affected cerebrum in stroke?
The necrotic core
The penumbra
51
Two types of cell death in the ischaemic penumbra?
Necrotic
Apoptotic
52
Treatment for AF?
Warfarin
53
Main types of stroke syndromes?
TACS - total anterior circulation syndrome
PACS - partial anterior circulation syndrome
Posterior circulation syndrome (basilar/vertebral/posterior cerebral)
Lacunar anterior circulation syndrome
54
Two main arteries supplying the basal ganglia?
Recurrent medial striate artery
Anterior choroidal artery
55
What's a watershed infarct?
Infarct in the periphery of two arterial territories
56
Types of haemorrhagic strokes?
Supratentorial
Cerebellar
Pontine
Subarachnoid haemorrhage
57
Main symptom that distinguishes a haemorrhage from a stroke?
Sudden onset severe headache, followed by neurological signs
58
Symptoms of total anterior circulation syndrome?
deterioration of conscious level
Contralateral homonymous hemiplegia
Contralateral hemisensory deficits
59
Symptoms of partial anterior circulation syndrome, of the anterior cerebral artery?
Contralateral hemiparesis (leg more)
Mild/non existent sensory deficit
Apathy/disinhibition
60
Symptoms of partial anterior circulation syndrome, of the middle cerebral artery?
Contralateral hemiplegia (arm more)
sensory deficit
hemianopia
aphasia/neglect
61
Symptoms of posterior circulation syndrome, of the posterior cerebral artery?
Hemianopia
amnesia
occulomotor/language disturbances
62
Symptoms of posterior circulation syndrome, of the vertebral artery?
(only supplies the posterior inferior cerebellar artery)
Laterally medullary syndrome
- ipsilateral limb ataxia
- ipsilateral horners
- contralateral sensory loss to limbs
63
Two types of basilar artery syndromes?
Complete basilar artery syndrome? (most of pons and medulla);
- Impairment of conscious level
- bilateral motor + sensory dysfunction
- cranial nerve signs
'Top of the basilar' syndrome (midbrain/thalamic/temporal/occipital):
- hemianopia/cortical blindness
- amnesia
- vertical gaze palsies
64
One perhaps promising stroke treatment?
IL-1 receptor antagonists
65
main functions of complement?
Lysis
| Opsonization
66
What's the choroid plexus?
Barrier between blood and CSF
Secretes CSF
67
Two categories of descending motor pathways?
Lateral
ventromedial
68
Two tracts in the lateral descending motor pathways?
Rubrospinal
Corticospinal
69
Where do fibres from the corticospinal tract arise?
The Primary motor cortex
The association motor cortex
Somatosensory areas
70
lesions to both lateral tracts often cause what?
What does it not cause a deficit in?
Loss of fine motor control
slower and less accurate movement
Can still stand upright however
71
A lesion to only the corticospinal tract cause what?
Intially the same deficits as a lesion to both of the tract in the lateral pathway
However the rubrospinal tract has plascticity and will take over some of the corticospinal tracts roles, apart from fine motor control.
72
What are the 3 ventromedial pathways?
Vestibulospinal tract
Tectospinal tract
Reticulospinal tract
73
What is the flexion crossed extension reflex?
When a cutaneous afferent causes contraction of a flexor and relaxation of an extensor, in reaction to noiceceptive input.
74
What are central pattern generators?
Examples?
Circuits that are hardwired into the CNS that do not need to be learned.
Key components of locomotion
respiration
mastication
Swallowing
75
Stages of the motor loop, involved in generating a voluntary muscle movement in the brain?
Feeds in from sensory cortex and prefrontal cortex will then relay to the VLN (through pons/cerebellum and basal ganglia) which will relay back to the Primary motor cortex, programme is stored in association motor cortex, which will fire if the depolarisation is above threshold
76
Three areas of the cerebellum, their roles?
Spinocerebellum - muscle tone/coordination
Cerebrocerebellum - planning, storing of procedural memory
Vestibulocerebellum - balance, eye movement coordination
77
What is the cerebellar motor loop?
When the cerebellum projects directly to the VLN, allowing direct movement
78
3 different structures of synapses?
One to one
Many to one
One to many
79
Mechanisms of plasticity in the CNS?
Presynaptic: increase or decrease transmitter release
Postsynaptic: increase or decrease in signal transduction
Recruiting silent synapses
80
In simple animals how does habituation and sensitisation occur?
Both caused by the response of the post-synaptic cell
Habituation is caused by the desensitisation of the Voltage Dependent Calcium Channel (VDCC)
Sensitisation is caused by increased calcium influx
81
In mammals what is long term potentiation? How does it occur?
Synapses that fire more (higher frequency) will be strengthened
Mostly through activated NMDA receptors that activate CAM kinase, which do several things to strengthen a synapse:
Phosphorylate AMPA receptors
Recruit more AMPA receptors
Cause increased neurotransmitter release
82
In mammals what is long term depression? How does it occur?
Synapses with low frequency signals will weaken
Pre-synaptically: Decreased glutamate release due to decreased VDCC
Post-synaptically: Dephosphorylation of AMPA receptors
83
How do dendritic cells present viral peptides to T-lymphocytes if they are not infected?
Can activate MHC class I to present a viral peptide
84
How do T-cells return to the place that the APC cell was activated?
Through up-regulation of specific adhesion molecules
85
Difference in Th1 and Th2 cells?
Both will stimulate the production of B-cells
Th1 is mostly involved in fighting parasites (eosinophils/basophils)
Th2 cells are mostly involved in fighting bacteria/viruses (macrophages)
86
What do Tc cells use to perforate cells, two types?
Use cytotoxic proteins:
- Perforin
- Granzymes (A and B)
87
How do perforin and granzymes interact to produce cell death?
Perforin makes pores in the cell surface membrane and granzymes will activate apoptosis in the cell, moving through pores made by perforin.
88
What's myelitis?
Infection of the spinal cord
89
The ability to recover from a spinal cord injury is determined by what factors?
Age
Characteristics of the lesion
Effect of experience
Training
90
Two categories of brain tumours? examples?
Intrinsic: glioma
Extrinsic: meningioma
91
Four types of haematoma?
Extra-dural
Acute sub-dural
Intracerebral
Intraventricular
92
Two different appearances of a scan of a subdural and an extradural haematoma?
Acute subdural - crescent (long and thing)
Extra dural - fatter look like a lemon
93
Four types of brain herniation?
Subfalcine
Tentorial (uncal)
Tentorial (central)
Tonsilar
94
What pathway promotes sleep?
VLPO (GABA) pathway
95
What neurotransmitters promote wakefulness?
NA, Histamine, Dopamine, Ach, glutamate
96
Hypnotic medications?
Benzodiazepines
Melatonin receptor agonists
Histamine receptor antagonists
Antidepressants
97
Stages of swallowing?
Buccal - voluntary
Pharyngeal
Eosophageal
98
What is degulation?
Swallowing
