where are the cell bodies of nociceptors located
dorsal root ganglion
trigeminal ganglia
what is allodynia
innocuous stimuli now elicits pain
what fibres are first pain mediators
A delta
What fibres mediate second pain response
c fibres
what is the primary transmitter in pain transmission between nociceptors and second order neurones
glutamate
what things suppress glutamate transmission
interneurons releasing GABA or glycine suppress transmission as do opiates and cannabinoids
What tracts in the spinal cord are the nociceptive tracts
spinothalamic
spinoreticular
what is the spinothalamic tracts role in pain transmission
A delta pain from lamina I terminated in posterior nucleus of the thalamus
Neurones from lamina v terminate in the posterior and ventroposterior nucleus of the thalamus.
Pain perception requires simultaneous firing in both pathways
Mediated first pain and temp
What is the spinoreticular tracts role in pain
largely transmits c fibre pain
connects with periaqueductal grey matter and parabrachial nucleus
involved in autonomic response to pain, arousal and fear of pain
what is the difference between pain and nociceptin
nociception may occur in absence of pain
pain is awarenedd of suffering
what fibres prevent pain when nociceptors are activated
A beta
what is gate control theory
the theory that not all nociceptive signals reach the brain as ‘pain’
where does the gate control theory occur
substantia gelatinosa
what are thermoreceptors
neurones that are specialised to respond to small changes in skin temperature
define dendrite
receive inputs from other neurones and convey graded electrical signals passively to soma
what is the axon hillock
site of initiation of the all or none action potential
define axons
conducts output signals as action potentials to other neurones
define synapse
point of chemical communication betweene neurones
where are unipolar neurones
peripheral autonomic neurones
where are pseudounipolar
dorsal root ganglion
where are bipolar neurons
retinal bipolar neurone
where are multipolar neurones
lower motor neurone
what is membrane resting potential
-70
what is threshold potential for AP
-60
what is overshoot
when the cell becomes positively polarised briefly during the AP
What is undershoot
when the cell becomes more negative after the AP
What ion channel mediates the upstroke and what mediated the down stroke
upstroke - sodium
down stroke potassium
what is the predominante intracellular cation
potassium
what is the predominant extracellular cation
sodium
name the demyelinating disorder of the PNS
guillian barre
what is the most common types of synapses
axodendritic
axosomatic
what is the exhitory transmitter in the CNS
glutamate - causes depolarisation
what is the inhibitory transmitter in the CNS
GABA or glycine - hyperpolarises the cells and prevents action potentiasl
cation
positive
anion
negative
What is spatial summation
many inputs converge upon a neurone to determine its output
What is temporal summation
a single input modulates the output by variation in action potential frequency of that input.
where are amino acids and amines released from
synaptic vesicle
where are peptide released from
secretory vesicles
what ion channels mediate fast neurotransmission
ionotropic ligance gated ion channels
what channels mediate slow neurotrnamission
g protein coupled receptors
what ion induces the release of neurotransmitters in the pre synaptic cleft
calcium
what neurotransmitters occur in all cells
glutamate and glycine
How are neurotransmitters made
within the neurone themselves
made in rER and packaged in Golgi apparatus - then transported to presynaptic terminal by axoplasmic transport where they are stored in vesicles.
what is the extracellular anion
chloride
what ions are excitatory and which are inhibitory
excitatory = sodium and calcium
inhibitory ie cause hyperpolarization = chloride and potassium
what drug antagonises sodium channels
lidocaine
favours inhibition
what is the name of receptors that are an integral component of the channel they control
ionotropic receptors
involved in direct gating
what is the name of receptors whose channels they control are distinct from the recetpors
metabotropic receptors (G protein coupled receptors)
involved in indirect gating
name monoamine neurotranmistters
5-HT
histamine
acetylcholine
Name catecholamines
noradrenaline
dopamine
adrenaline
name amino acids
glutamate
GABA
glycine
what shape of channels are glutamate receptors
tetramers
what shape of channels are gaba, glycine and ACh receptors
pentamers
what receptor doe benzodiazepines work on
GABAa - enhance chloride entry
what receptor does baclofen work on
agonist of GABAb - enhances K current - inhibition
what is an interneurone
a locally acting neurone, typically releases GABA and so brings about and IPSP and inhibition, function is local progressing of information
what is a projection neuron
a neuron responsible for conveying signal to other parts of the brain, typically releases glutamate so brings about epsp
what is a quanta
refers to the release of neurotransmitter from a single vesicle
how does a neuron discharge in the absensce of an inhibitory input
rhythmically - inhibitory inputs suppress some action portentials resulting in a irregular pattern of discharge
