Pain & Pain Management Flashcards
Activation of neural pathways by stimuli that damage or threaten to damage tissues, is known as?
Nociception
What is noxious stimuli?
Potentially damaging stimulus
What activates nociceptive pathways?
Nociceptive stimuli
Pain that is felt in one part of the body but is actually caused by pain or injury in another part of your body is known as?
Referred pain
What is congenital sensitivity?
A rare condition that inhibits ability to perceive physical pain
What term is used to describe inflammation of gum tissue around wisdom teeth?
Acute pericoronitis
When is the term used to describe when a blood clot at site of extraction fails to develop, dislodge or dissolve before the wound has healed resulting in intense pain?
Dry socket
What does CMD stand for?
Craniomandibular dysfunction
Lasting pain in areas of skin, usually after shingles, is known as?
Post herpetic neuralgia
What is the result of trigeminal neuralgia?
Sudden, severe facial pain
What is another term for neuroma?
“Pinched nerve”
What is a neuroma?
Benign growth of nerve tissue
What part of the brain stem does the trigeminal roots enter/exit?
Pons
What is the site of the first synapse in the dental pain pathway?
Caudalis
What is unique about the trigeminal mesencephalic nucleus?
It is the only example of primary afferent cell bodies in the CNS ( however it does not synapse!)
-70mv is the voltage that signifies what?
The resting membrane potential
What is a voltage gated channel?
Opens or closes with a change in voltage
What is an example of a voltage-gated channel?
Sodium channel
What is the effect on membrane potential of opening sodium channels?
There is an increase in membrane potential
Define depolarisation
An increase/ rise in membrane potential
What is the refractory period?
A period where an action potential cannot be triggered. Usually follows initiation of action potential.
What happens to sodium channels during the refractory period?
They have to reset to resting state and are closed
Why is the refractory period important?
So that action potentials flow in one direction
What is the effect of opening potassium channels on membrane potential?
The membrane potential decreases
Define hyperpolarisation
Where membrane potential decreases
How does myelination increase conduction velocity? Give two reasons.
- By acting as an electrical insulator, reducing loss of depolarising current across the plasma membrane.
- Allows voltage across membranes to change much faster- action potentials ‘jump’
What is the slowest class of axon and why?
C- fibre
It is the thinnest/smallest and is not myelinated
What is the fastest class of axon and why?
A- alpha
Thickest and myelinated
Where are graded potentials found? And what are they in response to?
In the post-synaptic nerve, in response to neurotransmitter binding to a chemically gated channel that opens.
Are graded potentials variable or fixed in height, duration and size?
Variable
Is an action potential variable of fixed in duration?
Fixed
What triggers an action potential?
Voltage
Name the group of membrane receptors that are affected by high temperatures
TRPV channels
Why does hot mint tea also feel cool?
Activates cold receptors
What is the difference between nociception and pain?
Nociception is a physiological process where the body detects damaging or potentially damaging stimuli. Pain is a sensation.
Which parts of the body lack nociceptors?
Brain and lung
How is substance P released from nerve endings?
Axon reflex
Pain due to stimulus that does not normally provoke pain is known as what?
Allodynia
What is the mode of NSAIDs?
They block sensitisation of nerves
Name the three theories of dentinal sensitivity
- Odontoblast theory
- Dentine innervation theory
- Hydrodynamic theory
Which dentine hypersensitivity theory is most commonly accepted?
Hydrodynamic theory
Why is the pain experienced by application of a cold stimulus to the tooth worse than from a hot stimulus?
Cold stimulus would cause fluid in dentinal tubules to flow outward. Heat would cause fluid to flow inwards. Outward flow of fluid stretches sensitive ion channels which results in more pain.
What phenomenon results from divergence of primary afferents and their convergence on to 2nd order neurons?
Referred pain
What is the nature of the ‘gate’ in gate control theory?
Mechanism where pain signals can be let through or restricted. Involves inhibitory neurotransmitter which can prevent chemical message being passed on any further.
Rubbing your hand after hitting it activates mechanoreceptors, shutting ‘gate’ and Lessing the pain. What is this an example of?
Segmental control
What happens to sodium ions when an action potential is initiated?
They move inside the cell membrane
What type of signalling are graded and action potentials?
Electrical
Why are action potentials required?
In nerves, signals decay over 2-3mm, action potentials;as are required as propagating signals
What term is used to describe large protein ions?
Anions
What voltage is resting membrane potential at?
-70 mv
At resting potential where is Na+ more concentrated?
Outside the cell
At resting potential where is K+ more concentrated?
Inside the cell
What ion drives resting membrane potential and why?
K+, as it has greater membrane permeability
What uses ATP to transport Na+ out of cells and K+ into cell, helping to maintain concentration gradients?
Sodium-potassium pump
What ion is the cell membrane most permeable to?
K+
What are the 5 stages of nerve conduction?
- resting membrane potential
- depolarisation
-rapid depolarisation overshoot - repolarisation
- hyper-polarisation
What voltage is threshold for action potential?
-50mv
What is the voltage when a membrane rapidly depolarises?
+30 mv
What happens to voltage gated Na+ channels when depolarisation of a membrane occurs?
They open and Na+ flows inside the cell
What happens to ion channels when rapid depolarisation overshoot occurs?
Na+ channels inactivate, K+ channels open after delay
What is the voltage when a membrane repolarises?
-70 mv
What happens to ion channels on repolarisation of membrane?
K+ open and flow out of cell
Na+ channels are inactivated
What is the voltage upon hyperpolarisation of a membrane?
-90 mv
What happens to ion channels when hyperpolarisation of a membrane occurs?
K+ channels close
Na+ channels reset
What is the stage after hyperpolarisation of a membrane?
Back to resting potential
What is the feedback loop called that’s associated with depolarisation, with Na+ channels opening to allow Na+ to move into cells?
Hodgkin’s cycle
Why do action potentials only flow in one direction?
So not to confuse signal transmission
What is an absolute refractory period?
Where Na+ channels are not in resting state so an action potential cannot occur
What is the relative refractory period?
Where K+ channels open and the membrane is hyperpolarised. So an action potential can occur, but requires large stimulus to do so.
What two factors does nerve conduction velocity depend upon?
- width of axon
- myelination
Which classification of nerve is the fastest?
A. C fibre, B. A- beta fibre, C. A- alpha fibre, D. A- delta fibres
C. A- alpha fibres
Which classification of nerve is the slowest?
A. C fibre, B. A- beta fibre, C. A- alpha fibre, D. A- delta fibres
A. C fibre
Define afferent
Nerves that go from periphery’s to CNS
Define efferent
Nerves that go from CNS to periphery’s
What is the structure of voltage gated Na+ channels?
4 domains made up of 6 segments
What is the most important domain in the voltage gated Na+ channel structure and why?
The yellow domain, it is made up of positive amino acids, responds and moves during depolarisation.
LA works by blocking Na+ channels. What domain in Na+ channel structure does it target?
The yellow domain
Where do cell bodies not exist, with the exception of the trigeminal mesencephalic nucleus?
CNS
What is the first stage in the trigeminal sensory pathway?
- Primary afferent neurones in trigeminal ganglion in Peripheral nervous system
What is the second stage of the trigeminal sensory pathway?
- Neurone synapses at the trigeminal sensory nuclei in the CNS
What tract do second order neurones from the trigeminal sensory nuclei pass along in order to reach the thalamus?
Trigemino-thalmic tract
What is stage 3 in the trigeminal sensory pathway?
Synapse of second order neurones at thalamus
What is stage 4 in the trigeminal sensory pathway?
Neurones pass to higher centres in somatosensory cortex
What are the peripheral trigeminal nerve divisions?
- ophthalmic
- maxillary
- mandibular
What is the ganglion in the peripheral trigeminal region?
Trigeminal ganglion
Where do cell bodies for nerves of teeth exist?
In the trigeminal ganglion
How many roots are there in the peripheral trigeminal nerve? And what are they?
Two:
- sensory
- motor
Where does the trigeminal nerve exit and enter the CNS?
The pons
What are the four zones of the trigeminal sensory nuclear complex?
- trigeminal main sensory nucleus
- nucleus oralis
- nucleus interpolaris
- nucleus Caudalis
What type of nerves does the trigeminal mesencephalic nucleus contain?
Primary afferent nerves
Which zone of the trigeminal sensory nuclear complex is out-with the skull?
Nucleus Caudalis
Where is the site for synapses for pain and hot/cold sensations?
Trigeminal Nucleus Caudalis
What will occur if the trigeminal nucleus Caudalis becomes damaged?
Ipsilateral loss of facial pain and hot/cold sensation
Where is the centre where afferent nerves from teeth are processed?
Trigeminal nucleus oralis
What would happen if damage to the main sensory nucleus occurs?
Ipsilateral loss of touch to the face
What division of the peripheral trigeminal nerve is the motor root associated with?
Mandibular division
Where can cell bodies for jaw muscle spindle afferents and some mechanoreceptive afferents from PDL be found?
Trigeminal mesencephalic nucleus
Where are primary afferent cell bodies usually not found?
CNS
Uniquely, what primary afferent cell body is found in the CNS?
Trigeminal mesencephalic nucleus
Do nerves synapse at the trigeminal mesencephalic nucleus? Yes or no?
No
What nerves of the peripheral trigeminal nerve is the trigeminal mesencephalic nucleus associated with?
Motor nerves at trigeminal motor nucleus
Where does the trigeminal motor nucleus sit in relation to the main sensory nucleus in the pons?
Medially
What does the trigeminal motor nucleus supply?
Muscles of mastication via motor root of CN V3
