Adam Smith and Jessica Adamczak

1

• Adam Smith and Jessica Adamczak

2
History

• Derived from the word Latin poena punishment, a
  fine, a penalty.
• Early Civilization Associated pain with
  religion, magic, chi, frustration.
• Plato The heart and liver were the centers for
  perception. Pain came from a combination of
  peripheral sensation and the perception of the
  soul.

3
More History

• Aristotle The brain has no part in perception.
• Galen Gave brain credit. Defined anatomy of
  Cranial and Spinal Nerves. Hard nerves, soft
  nerves, pain nerves.

4
Even More History

• Descartes Defined pathways from peripheral
  systems to the brain.
• Specificity Theory Pain is a specific sensation
  and is not associated with regular sensation.
• Intensive Summation Theory Pain is a
  continuation of normal sensation beyond a certain
  pain threshold.
• Pain is more complicated than these theories
  explained.

5
Current Theories

• Pain is now known to be a complex relationship
  between the physical detection of pain
  (nociception), non-painful physical stimuli,
  environmental factors, psychological factors, and
  various inhibitory systems.

6
Physiology

• Nociceptor Free nerve ending that detects
  painful stimuli
• Three Types Mechanical, Chemical, Thermal.
• Nociceptors are mostly located in the skin but do
  exist in the periosteum, joints, and some in deep
  tissue or viscera.
• There is no habituation of nociception.

7
Nociceptors

• Ad Fast transmission fibers. These fibers
  transmit signals at about 20 meters per second.
• C Slow transmission fibers. These fibers
  transmit signals at less than 2 meters per second.

8
Ad

• Mostly associated with acute pain.
• Myelinated axons allow faster transmission
  speeds.
• Associated with avoidance reflexes.
• Sense temperature (mostly cold), and mechanical
  pain.

9
c

• Unmyelinated axons transmit signals at much
  slower speeds.
• Associated with dull, slow, aching, chronic pain.
• Detect temperature (warm), mechanical, and
  chemical pain.

10
Path of Pain

• Transduction Nociceptors detect pain and
  translate it into electrical signal.
• Transmission The signal is propagated through
  afferent nerves to the dorsal ganglia.

At this point, the path changes depending
whether it was a fast or slow signal.
11
Spine

• The dorsal horn of the spine is separated into
  different sections called lamina.

Dorsal horn
12
Neospinothalamic Path

• For Ad fibers
• Synapes with the lamina marginalis
• Travels to the thalamus Pain is perceived
• Travels to the somatocensory cortex Pain is
  localized

13
Paleospinothalamic Path

• For C fibers
• Synapses with substantia gelatinosa (lamina 2 and
  3)
• Travels mostly to brain stem -
• 10 go to thalamus
• The remaining signals go to the pons,
  mesencephalon, and the medulla.
• This pain is poorly localized.

14
References

• http//www-medlib.med.utah.edu/pain_center/educati
  on/outlines/noci_transduc.html
• Kandel E.R., Schwartz, J.H., Jessell, T.M. 2000.
  Principles of Neural Science, 4th ed.,
  pp.472-479. McGraw-Hill, New York.
• Dahl JB, Moiniche S (2004). "Pre-emptive
  analgesia". Br Med Bull 71 13-27.
• Liem EB, Joiner TV, Tsueda K, Sessler DI.
  Increased sensitivity to thermal pain and reduced
  subcutaneous lidocaine efficacy in redheads.
  Anesthesiology. 2005 Mar102(3)509-14.
• Guyton Hall, (2005), Textbook of Medical
  Physiology (11th edition), Elsevier-Saunders
• http//www-medlib.med.utah.edu/pain_center/educati
  on/outlines/noci_transduc.html
• http//www.georgiapainphysicians.com/downloads/m1_
  slides/5.20Dorsal20horn.jpg