Chapter 48 Flashcards
What are some major characteristics of slow pain? What kind of fibers carry slow pain?
- slow, burning, aching, throbbing, nauseous and chronic
- carried by Type C fibers and typically onset over 1 second or more
What are some characteristics of fast pain? What kind of fibers carry fast pain?
Fast pain has a quick onset of about 0.1 second.
- sharp, pricking, acute, and electric
- Carried by A-delta fibers
Which of the two pains (fast and slow) are deeper and associated with tissue destrction?
Slow pain
What are the three type of stimuli that elicit pain?
- Chemical (slow)
- Thermal (fast and slow)
- Mechanical (fast and slow)
What kind of receptors are pain receptors?
-free nerve endings
Do pain receptors display adaptation? What is the chemical reasoning?
- No
- prostaglandins decrease the threshold for pain stimulus and cause HYPERALGESIA which keeps the person apprised of a tissue damaging stimulus
What Ion concentration directly correlates to intensity of pain?
K+ ion concentration
What enzyme concentration will correlate with pain intensity? Why?
- Proteolytic enzymes
- attack the nerve endings and make them more permeable to ions
How does tissue ischemia cause pain?
-build up of lactic acid as well as bradykinin and poteolytic enzymes signal cell damage and elicit pain
What determine how quickly pain due to ischemia appears?
-rate of metabolism of the tissue
What two actions of a muscle in spasm cause pain?
- direct stimulation of mechanosensitive pain receptors
- compression of vessels leading to tissue ischemia
What two kind of fibers bring pain into the spinal cord?
- A delta fibers (fast sharp pain)
- C fibers (slow chronic pain)
What is the significance of this “dual innervation” of pain?
-The fast Adelta fibers alert the person to the pain quickly and then the C fibers come into play about a second of so later and then progressively get worse. The C fibers keep ther person aprised of the insult.
Which tract (neospinothalamic or paleospinothalamic) carry mechanical and acute thermal pain?
-neospinothalamic
Which neurotrasmitter is used in the neospinothalamic pathway in the transmission of mechanical and acute thermal pain through Adelta fibers?
-glutamate (excitatory)
What type of pain and fiber is carried in the paleospinothalamic pathway?
- Chemical chronic pain
- slow type C fibers
*think Paleo=old and old people have chronic pain
What type of neurotransmitter is used in the paleospinothalamic pathway?
-GLUTAMATE AND SUBSTANCE P
Where in the dorsal horn do paleospinothalamic pathway type C fibers terminate? Where do they go after that?
–lamina II and III (substantia gelatinosa)
-Then they meet up with the fibers from the fast pain pathway and follow them.
How is a cordotomy used to relieve chronic pain? Is is always successful? Why or why not?
- The anterolateral quadrant of the thoracic spinal cord is cut to relieve chronic pain
- Not always successful becuase other areas of the spinal cord then become sensitized to pain and sensation that they were not before
Why is it so hard to sleep when one is in chronic severe pain?
- Pain fibers innervate the reticular formation as well as the intralaminal nuclei of the thalamus and project onto the cerebral cortex
- constitutes the main system of arousal in the human brain.
Why is pain from the viscera referred to somatic dermatomes?
- branches of visceral pain fibers synapse in the spinal cord on the same second order neurons that somatic pain fibers do
- Pain from the viscera is conducted through some of the same nerves as somatic pain therefore the signals can become “confusing” to the cortex.
What are common causes of visceral pain?
- Ischemia
- Chemical stimuli (leaking Gi juices)
- Spasm of hollow viscus
- Distention of hollow viscus
Which viscera are very sensitive to pain?
- bile ducts
- bronchii
- parietal pleura
What is the difference between primary and secondary hyperalgesia?
- Primary hyperalgesia is due to hypersensitivity of the pain receptors themselves (sunburn)
- secondary hyperalgesia is due to facilitation of the sensory transmission (lesions in the thalamus or spinal cord)
