Pain Flashcards
What is pain?
An unpleasent sensory and emotional experience associated with real or potential tissue damage, or described in terms of tissue damage.
What are the types of pain?
- Fast, stabbing pain: Result of Aδ fibres due to faster conduction velocities.
- Slow, burning pain: Result of C fibres with lower conduction velocities.
What are the types of spinal cord neurones that respond to pain?
- Lamina I neurones only receive inputs from nociceptive fibres and only respond to pain so are known as narrow dynamic range (NDR) cells.
- Lamina V neurones receive inputs from both nociceptive and somoatosensory fibres so respond to touch at low stimuli intensities and pain at high intensities, so are know as wide dynamic range (WDR) cells.
What are the main areas of the cortex that respond to pain?
- Somatosensory cortex: Involved with the sensory component of pain detection.
- Anterior cingulate cortex (ACC): Part of the limbic system involved with mediating emotional response to pain. Also involved with empathetic pain (pain caused by seeing other people in pain).
- Insula: Involved in homeostasis and so forms part of the homeostatic response to pain.
Which areas of the brain give descending fibres involved in gate-control of pain?
- Periaqueductal grey (PAG)
- Raphe nucleus
- Nuclei of rostral medulla
What is nociception?
The neural process of encoding noxious stimuli
What channels are associated with noxious heat?
- TRPV1
- TRPV3
- Anoctamin 1 (ANO1)
What channels are associated with noxious cold?
- TRPM8
- TRPA1
What channels are assciated with protons?
- ASICs (acid-sensing ion channels)
- TRPV1
- TASKS
What channels are associated with noxious mechanical stimuli?
Peizol 1/2 (possible TRPV4, ASICs)
What channels are associated with noxious ATP?
P2X3
What are external noxious stimuli?
- Mechanical
- Temperature
- Chemical
What are internal noxious stimuli?
- ATP
- Bradykinins
- Acid
What is the pain threshold for heat?
~42o
What are the types of pain sensitisations?
- Allodynia: Reduction in pain threshold
- Hyperalgesia: Same intensity of stimuli causes more pain
What are the important sensitisation factors?
- NGF
- PGE2