Search our site 
 
Advanced Search
 
Home | Exam dates | Contact us | About us | Testimonials |
 
 

map
You are in Home >> Resources >> Clinical anaesthesia >> Acute pain


Physiology of pain

Created: 13/7/2004
 

Figure 4: Physiology of pain




Figure A:

Antinociceptive pathways are activated when pain signals in the spinothalamic tract reach the brain stem and thalamus. The periaqueductal gray matter and nucleus raphe magnus release endorphins and enkephalins. A series of physicochemical changes then produce inhibition of pain transmission in the spinal cord.

Figure B:

70% of endorphin and enkephalin receptors are in the presynaptic membrane of nociceptors. Thus, most of the pain signal is stopped before it reaches the dorsal horn. The signal is then further weakened by dynorphin activity in the spinal cord. The site of action of various analgesics is shown.

Figure C:

Dynorphin activation of alpha receptors on inhibitory interneurons causes the release of GABA. This causes hyperpolarisation of dorsal horn cells and inhibits further transmission of the pain signal.

Implications for pain therapy:


Medications that mimic the effects of endorphins and enkephalins are the mainstays of chronic pain therapy. Newer drugs that mimic or potentiate the effects of GABA or alpha-2 receptor agonists have made it possible to target therapy for chronic pain syndromes.
ArticleDate:20040713
SiteSection: Article
 
   
    
                                            
  Posting rules

     To view or add comments you must be a registered user and login  




Login Status  

You are not currently logged in.
UK/Ireland Registration
Overseas Registration

  Forgot your password?








 
All rights reserved © 2018. Designed by AnaesthesiaUK.

{Site map} {Site disclaimer} {Privacy Policy} {Terms and conditions}

 Like us on Facebook 

vp