Topic 8.3 Flashcards
What is pain?
Unpleasant sensory and emotional experience associated with actual or potential tissue damage
What is the usual type of R of pain R?
free nerve endings
What is analgesia?
Treatment that causes insensibility to pain without loss of consciousness
What is chronic pain?
pain longer than 12 weeks despite medication / treatment
What is congenital pain insensitivity?
one cannot feel pain due to genetic causes
What is syringomyelia?
cyst formation in the spinal cord that leads to loss of pain sensation
2 examples of analgesics
- narcotics (opioid)
- NSAIDS (non steroidal anti-inflammatory drugs)
What are the 3 types of pain?
- Nociceptive pain
- Neuropathic pain
- Central pain
Types of nociceptors and their fiber (3)
- thermal nociceptors (Ad)
- mechanical nociceptors (Ad)
- polymodal nociceptors (C)
A delta fibers projection
Rexed lamina I, V
C fibers projection
Rexed lamina II (substantia gelatinosa)
A beta fibers projection
Rexed lamina IV
What is TRPV1 and what activates it (3)?
capsaicin receptor
- noxious heat
- acid
- capsaicin (chili)
What activates TRPV2?
Temperatures above 52°C
What activates TRPV3? (2)
- temperature above 34°C
- camphor
What activated TRPV4?
temperature above 27°C
What activates TRPM8? (2)
- temperature below 28°C
- menthol
What activates TRPA1? (2)
- temperature below 18°C
- mustard oil
3 nociceptive pathways
- Spino thalamic tract
- Spino reticular tract
- Spino mesencephalic tract
Types of projection neurons spinothalamic tract (2)
- Wide-dynamic-range neuron
- Nociception-specific neuron
Types of spinothalamic tracts (2)
- neospinothalamic tract
- paleospinothalamic tract
What does the neospinothalamic tract detect? (2)
sensory component of pain, location
What does the paleospinothalamic tract detect? (2)
emotional component of pain + autonomic reactions
Where does the paleospinothalamic tract project? (4)
- association cortex
- cingulate
- prefrontal
- insular
Where is the projection neuron of spinoreticular tract
located in rexed laminae VII and VIII
Course of spinoreticular tract (3)
- reticular formation (pons)
- medial nuclei of thalamus
- somatosensory cortex
What is spinoreticular tract responding to?
alarming arousal reaction
Where is the projection neuron of spinomesencephaic tract?
located in Rexed lamina I and V
Where does spino mesencephalic tract project?
periaqueductal gray matter
Types of change in pain sensitivity (3)
- Hyperalgesia
- Allodynia
- Referred pain
3 types of hyperalgesia
- primary
- secondary
- central
Which molecules can trigger primary hyperalgesia? (6)
local inflammatory substances like
- bradykinin,
- prostaglandins,
- serotonin,
- substance P,
- H+, K+
Mediators of secondary hyperalgesia (4)
- CGRP (vasodilators)
- Histamine
- Bradykinin
- Substance P
What is the gate control theory?
the ability of low-threshold fibre activation to reduce pain
What happens in the gate control theory?
The projection neurone is excited by sensory neurons (C and Ab) and inhibited by interneurons in the superficial dorsal horn
What is a monoaminergic molecule?
a chemical which functions to directly modulate the neurotransmitter systems in the brain
3 way of regulation of pain sensation
- gate control theory
- regulation of nociceptive neurons in SP by descending monoaminergic pathways
- neurons in the endogenous analgesia pathway
Which peptides are derived from POMC? (3)
- b endorphin
- endormorphin 1
- endomorphin 2
Which peptides are derived from pro enkephalin? (2)
- met enkephalin
- let enkephalin
Why peptides are derived from pro-dynorphin? (2)
- dynorphin A
- dynorphin B
Which peptide is derived from pro orphanin FQ?
Orphanin FQ
B endorphin receptor
mu / delta
Endorphin receptor
mu
Met enkephalin receptor
delta (majuscule?)
Let enkephalin receptor
delta
dynorphin receptor
kappa
Presynaptic effect of opioid peptides?
reduces duration of PSP by inhibiting VDCC and reducing the release of nt
Postsynaptic effect of opioid peptides?
hyperpolarization of postsynaptic neurons by activating K+ channels
