3.3 Flashcards
Pain receptors: free nerve endings
A𝛅 fibers: fast conducting
- relay sharp, short-term, well-localized pain
C fibers: slow conducting
- relay dull, persistent, poorly localized pain
Pain pathway: ALS system
Direct pathway: to thalamus
- A𝛅 fibers
Indirect pathway: to other brain structures
- C fibers
Indirect pain pathway of ALS system
Much of this pathway travels to the reticular system, then the thalamus
- Alerts patient to injury
- Elicits response → evade injury
OTHER DESTINATIONS
Mesencephalon
- Modulates pain reception
* Descending pain-inhibiting system
- Transmits to the amygdala
* Emotional component of pain
Superior colliculus
- Turn head/eyes toward pain stimulus
Hypothalamus
- Autonomic response
* Increases heart rate
* Endocrine release of stress hormone
Fear avoidanve
Specificity theory
Proposed that the somatosensory system could be divided according to specific receptors for tactile, hot, cold, and pain
Pattern theory
Suggested that in addition to the type of input (fibers, pathways, or anatomic structures), the pattern of impulses in the nervous system modulates pain perception
Gate control theory
Endogenous pain modulatory mechanisms could enhance or reduce perception
Diffuse noxious inhibitory controls
Observation that a localized nociceptive stimulation can produce a diffuse analgesic effect over the rest of the body, an analgesic approach known as counter-irritation.
Pain rehabilitation
The process of helping an individual achieve the highest level of function, independence, and quality of life possible through the management of a painful condition and its impact on daily activities.
What is the factor noted to “lower perceived disability due to pain”?
Patients with higher knowledge in pain neurophysiology have less fear avoidance and lower perceived disability due to pain.
What factor is “known to be one of the most important aspects of pain rehabilitation”? What is a major barrier to this?
Exercise
Fear avoidance belief leads to kinesiophobia; a way to reduce this is to educate patients about the neurophysiology of pain
Define hyperalgesia
Exaggerated response to normally painful simulation
How can primary and secondary hyperalgesia be explained?
Primary: release of different inflammatory factors in the periphery, which leads to the recruitment of nociceptors near the side of injury (potassium, prostaglains, bradykinins, histamine, substance P, and serotonins), which has the effect of recruiting nearby nociceptors and producing sensation; lower pain thresholds
Secondary: central phenomenon known as central sensitization; repeated recruitment of C fibers after an injury could have the effect of sensitizing the projection neurons in the dorsal horns of the SC; produces an increase in the action potential of spinal neurons called wind-up
The two extrinsic innervations are ___ and ___ and numerous intrinsic neurons contribute to our “gut feelings.”
vagal and spinal
There are often no clear pathways for visceral pain syndromes such as ____.
irritable bowel syndrome
