Pain Flashcards
what is nocicpetion generally associated with
an emotionally disturbing affect = we call it pain
what is pain
an abstraction of nociception
what is a nociceptor
free nerve ending
detect stimuli that caused damage to tissue or may cause damage
what type of stimulus is adequate to trigger the receptor/free nerve ending? (nociceptor)
can be intense mechanical stimulation, intense heat or cold, or various chemicals released by or in response to tissue damage
how do action potentials encode the stimulus?
they encode the strength of it based on their rate of firing (frequency modulation)
what happens regarding RP and AP’s when tissue is injured?
Nociceptors generate a receptor potential (local and graded/amplitude modulated)
If the receptor potential depolarizes the cell to its threshold, then action potentials are generated—info travels to the CNS and also causes reactions in the periphery at the site of injury
how are receptor potentials encoded?
local and graded (amplitude modulated)
What else occurs with tissue injury?
Nociceptor stimulation causes an axon reflex enhancing inflammation (with no synapse in the CNS which is unique)
what is released as a result of tissue injury?
Nociceptors release glutamate and other neuropeptides
what occurs at the site of damage
At the site of damage, there is release of K+ from the damaged cell/s, serotonin and chemicals such as substance P and calcitonin gene related peptide and secondary messengers such as bradykinin and histamine (some of the chemicals are from the damaged cells and others from the nociceptors)
what happens in the periphery in response to tissue damage?
In the periphery, these chemicals cause dilation of arterioles causing flare (redness)
And leakage of plasma from venules resulting in edema (swelling)
And proliferation of cells and attraction of phagocytes (for repair and cleaning away debris)
what causes redness in periphery due to damage?
dilation of arterioles causing flare in response to K+ from the damaged cell/s, serotonin and chemicals such as substance P and calcitonin gene related peptide and secondary messengers such as bradykinin and histamine
what causes swelling in the periphery in response to damage?
leakage of plasma from venules resulting in edema
what are phagocytes used for in the periphery?
for repair and cleaning away debris
what do the chemicals due to the nociceptive endings?
sensitize them, increasing susceptibility to pain in the injured area
