Flashcards in 022514 2 Pain SDL Deck (19):
What is nociceptive pain? What detects it?
pain due to inflammation
What is neuropathic pain?
pain due to nervous tissue damage
What is mixed pain?
pain due to cancer
What are three causes of neuropathic pain?
upregulation of neurotransmitter receptors
upregulation of sodium channels
sympathetic nerves sprout into sensory ganglia
What is a noxious stimulus?
an event that damages tissue (can be mechanical, chemical, or thermal).
What are three characteristics of first pain?
A-delta fiber mediated (30 m/s)
What are three characteristics of second pain?
not well localized
C fiber mediated (2 m/s)
Difference between nociceptor and polymodal nociceptor?
polymodal detects mechanical, thermal, or chemical stimuli simultaneously.
What is hyperalgesia?
increased sensitivity to pain
What causes primary hyperalgesia?
nociceptive fibers at wound site have lower threshold for activation and therefore increased firing frequency
What causes secondary hyperalgesia?
larger action potentials caused by increased synthesis of chemical receptors at synapses, and ion channels remaining open longer
What is allodynia? Why does it happen?
Pain due to stimulus that does not normally evoke pain. Occurs due to persistent nociceptive activation (chronic pain)
What is neurogenic inflammation?
inflammation due to release of substance P and calcitonin gene related peptide (CGRP) or silent nociceptors becoming more active
What does substance P do?
causes mast cells to release histamine
What does calcitonin gene related peptide do?
dilates peripheral blood vessels
What is the gate theory of pain control?
Small afferents keep pain gate open by inhibiting interneurons that inhibit pain tract cells. Large afferents close pain gate by exciting interneurons that inhibit pain tract cells.
GABA, glycine, opioids (beta-endorphin, endorphin, dysnorphin) serotonin, and norepinephrine are inhibitory or excitatory neurotransmitters?
What converts acute pain to chronic pain? How is it corrected?
Thalamocortical looping of pain to somatosensory cortex which continues after source of pain is removed. Lesion to central laminar thalamic nucleus.