11/29: Pain, Analgesia, and Anesthesia Flashcards
What is pain?
An unpleasant sensory and emotional experience associated with actual or
potential damage
What feelings are associated with higher intensity/moderate pain?
Anxiety and feelings to escape
What is is nociception?
Unconscious activity induced by a harmful stimulus to sense receptors
What are are noxious stimuli?
Harmful, poisonous and unpleasant stimuli
What is hyperalgesia?
Exaggerated response to a noxious stimulus
What is allodynia?
Sensation of pain in response to a normal stimulus that does not cause pain
i. I.E hot shower after being in cold weather
Does the threshold lower when intense stimuli are repeated or prolonged?
Yes
Does being exposed to the same stimulus cause a higher frequency of firing for all stimulus activities?
Yes
What inflammatory mediators contribute to the increased frequency and lowered stimulus?
Bradykinin
Nerve growth factor Prostaglandins
Leukotrienes
What do hyperalgesia and allodynia signify an increased sensitivity to?
Nociception
i. Essentially, both let body know you are doing something you were not aware of that is hurting you
What is analgesia?
Inability or reduced ability to feel pain
What substances reduces ability to feel pain?
Analgesics
What is insensitivity to pain called?
Anesthesia
What substances produce general insensitivity to pain?
Anesthetics
What general anesthetic is used often by dentist to perform surgery?
Nitrous
What local anesthetic is used by dentist to perform surgery?
Lidocaine
What are the 3 classes of receptors found in the body?
- Mechanoreceptors
- Thermoreceptors
- Chemoreceptors
What are the two transient receptor potential channels found in the body?
- TRPV1
- TRPA1
What protein does TRPV1 use?
Vanilloids
What do TRPV1 receptors respond to?
Heat
Acids
Chemicals
What protein does TRPA1 respond to?
Ankyrin
What is ankyrin used for?
Attaching cytoskeletal proteins together
What does TRPA1 respond to?
Mechanical
Cold
Chemical
What receptors are though to be the main ones dealing with acid induced pain?
ASIC receptors
What receptor does cold sensations activate?
TRPM8
i. “M for methanol”
1. Not really but helps remember it
What receptor does mechanical sensations activate?
TRPA1
What receptor does heat sensations activate?
TRPV1
What two receptors are used when ATP is released to cause pain?
P2X
P2Y
- Is P2X an ionotropic or G-protein receptor?
a. Ionotropic
- Is P2Y an ionotropic or G-protein receptor?
G-protein
What 6 molecules act on G-protein coupled receptors to cause pain?
(BHPSSC)
Bradykinin
Histamine
Prostaglandins
Serotonin
Substance P
Calcitonin-gene related protein
What receptor does NGF act on?
Tyrosine Kinase A
What does NGF singaling through a tyrosine kinase receptor A cause?
Gene transcription
- What does ATP cause once it has bound to either P2X or P2Y?
a. Immediate depolarization with P2X
b. Gene expression or Immediate depolarization with P2Y
- Can all three types of receptors cause sensitization of nociceptive neurons?
Yes
- What nerve type is the primary type used for pain transmission?
a. Sensory afferent neurons
- What are the two types of sensory afferent neurons?
a. A-Beta
b. A-Delta/C axons
- How do A-Delta and C-axons differ
a. A-delta is myelinated while C-Axons are not
- What type of stimuli does A-Beta nerves respond to?
a. Light touching and moving stimuli
- What type of stimuli does A-delta nerves respond to?
a. Extremely painful stimuli
- Where do these axons cross within the spinal cord?
Ventrolateral quadrant within the ventrolateral spinothalamic tract
What parts of the somatosensory cortex are activated by pain?
Primary and secondary
What laminae do the unmyelinated C-fibers project to within the dorsal horn?
Superficial laminae 1 and 2
What laminae do the myelinated A and Delta fibers project to in the dorsal horn?
Superficial laminae 1 and 5
- Where are somatosensory ganglia located at within the body?
a. Peripheral ganglia like DRG and Trigeminal ganglia
- Where do the spinothalamic tract axons ascend to?
Thalamus
- Where do the thalamic projections go to?
a. Somatosensory cortex
- What does the somatosensory cortex mediate?
Purely sensory aspect of pain
i. This is locations, intensity, quality
- Where do thalamic neurons project to?
a. Cortical regions
- What does the cortical regions of the brain link pain with?
Emotional responses
i. Why you remember painful events
Does visceral sensation travel along the same central pathway as somatic sensation in
the spinothalamic tract and thalamic radiation?
Yes
Are the cortical receiving areas for visceral sensation intermixed with somatic receiving areas?
Yes
What does this mixing between cortical receiving areas for visceral sensation and somatic receiving areas create?
Referred pain
What is the gate control mechanism for pain modulation?
Pain from nociceptive pathways can be interrupted by the addition of new stimulus to the site where the nerve is receiving the injury at
i. This is why rubbing shin after hitting it helps as new stimulus are generated and they use the same nerves
What do interneurons within the superficial regions of the dorsal horn contain receptors for?
Endogenous opioid peptides
What does activation of the postsynaptic opioid receptor do to the dorsal horn interneuron?
Hyperpolarizes it causing an uptake in K
What does activation of the presynaptic opioid receptor do to the dorsal horn?
Decrease in Ca so glutamate and substance P are decreased
What do these two actions do to EPSPs within the dorsal horn?
Reduce its duration
What is the main opioid used by dentists?
Morphine
What is the mechanism of action of an opioid?
- Bind to receptors located on neurons
- Decrease intracellular calcium causing reduced NT
- Increase intracellular potassium causing hyperpolarization decreasing action potential propagation
What are the two non-opioid analgesics used
Aspirin
Acetaminophen
- How do NSAIDs and aspirin work?
By inhibiting cyclooxygenase which causes a reduced production of
prostaglandins leading to a reduced inflammatory-mediated pain signaling and
nociceptor sensitivity
- What two components of an NSAID’s reduce inflammatory mediated pain signaling?
a. Histamine
b. Serotonin
