~Chapter 14 - Lecture Section 14.3 Flashcards
What is the function of pain?
Pain functions to warn us of potentially damaging situations
Are some people unable to feel pain?
Yes. Some people are born with a congenital absence of pain, those who are often die fairly early due to infections from their acquired injuries.
What is the Multimodal Nature of Pain?
Pain is often described as having sensory and emotional components. This might be because painful stimuli are so closely related to self-preservation
What are sensory-component descriptions of pain?
Prickly, sharp, throbbing, dull, burning
What are affective/emotional-component descriptions of pain?
Torturous, annoying, nagging
What is Nociceptive Pain?
These free nerve endings have specialized receptors to signal impending damage to the skin, this is where something is getting to be damaging, and you’re able to remove yourself from the situation before you are damaged.
What are free-nerve endings?
Nociceptors/pain receptors are free-nerve endings, they do not have specialized endings like Mechanoreceptors and are typically very small diameter axons
What are the different specialized Nociceptors?
There are Nociceptors that are specialized for heat, different chemicals, excessive pressure, and cold temperatures.
What is Inflammatory Pain?
Inflammatory Pain signals when you have done damage to tissues.
With Inflammatory Pain, damaged cells that are ripped open due to some kind of trauma leak an “inflammatory soup” of ___, ___, ___, ___, ___, ___, and ___.
K+ // Serotonin // Brandykinin // Histamine // Prostaglandins // Leukotrienes // substance P
K+, Serotonin, Brandykinin, and Histamine ___ Nociceptors.
activate
Prostaglandins, Leukotrienes, and substance P ___ Nociceptors to further stimulation.
sensitize
What is Neuropathic Pain?
Neuropathic Pain is caused by damage to the nervous system itself, and Nociceptor axons are aborantly stimulated without the sensation being present, causing you to feel pain.
in things like inflammation related to Carpal Tunnel syndrome, ___ firing of neurons from spinal cord injury or Stroke, these Nociceptive pathways can become activated ___ any damage to the skin, and will produce pain.
abnormal // without
What is the worst type of pain?
Neuropathic Pain is arguably the worst pain, because it is the hardest to treat because there is no tissue damage, and it doesn’t really serve an evolutionary advantageous role.
Painful stimuli, once they come up the ___ and make their way to the ___, spread out to and activate multiple subcortical + cortical areas
Spinalthalamic track // Ventral Posterior Lateral Nucleus
The Hypothalamus and Thalamus are ___ areas.
Subcortical
___, ___, ___, ___, and ___, are all Telencephalic areas.
Somatosensory Cortex (S1, S2) // Insula // Anterior Cingulate Cortex // Hippocampus // Amygdala
Where is the Insula located?
Buried underneath the outer shell of the Cortex
Where is Anterior Cingulate Cortex located?
Deep in the Cortex, just over the Corpus Callosum
What was the 1950’s Direct Pathway Model?
Stimulation of Nociceptor receptors → transmit signal to brain = feel pain
This is a purely bottom-up process that was a vast oversimplification
There is tremendous ___ of Nociceptive Sensations.
Top-down modulation
What is an example of Top-down modulation of Nociceptive Sensations?
There are many anecdotal reports that pain does not set in until the person realizes how injured they are.
What is Phantom Limbs Syndrome?
Feeling a lost limb is still present, and sensation of pain without Nociceptor stimulation
Painful sensations due to Phantom Limbs Syndrome can persist even when the subjects undergo surgery to lesion the afference all the way up to the ___. So it’s not the afference, it’s not the missing limb, it’s ___.
Dorsal Root Ganglion // Top-down modulation
Influences of Top-down modulation are ___ and ___.
multifaceted // complex
Who was the Gate Control Model proposed by?
Proposed by Melzack and Wall in 1965
What is the Gate Control Model?
Attempts to account for the many Top-down (thoughts, memories, expectations, emotions) influences on pain perception.
They suggested that the Gate Control System is located in the ___ of the ___. From the Spinalthalamic pathway, this is where these neurons are synapsing right off of the ___ of the Spinal Cord.
Substantia Gelatinosa // spinal cord // Dorsal Root
SG+ and SG- are innervated by ___.
L-Fibres
What are L-fibers?
Large diameter fibres with fast conduction velocities, which carry information about non-painful tactile stimuli from Mechanoreceptors.
L-fibres provide input/info to ___ and to ___.
SG- // Transmission cells
What are S-fibres?
Small diameter fibers with slow transmission velocity, and are associated with Nociceptors
S-fibres provide input/info to ___ and ___.
SG+ // Transmission cells
What is the Central Control?
Central Control captures all the Top-down inputs, and covers all the different ways in which Top-down can modulate the circuit.
What is a Transmission-cell (T-cell)?
The most important component of the Gate Control Model, which integrates all the inputs, so the activity level dictates the level of perceived pain.