Anatomy and physiology of pain Flashcards
Define pain
an unpleasant sensory and emotional experience associated with or resembling actual or potential tissue damage
why is pain important
it is necessary as it acts as a warning system
what is a noxious stimulus
a stimulus that is actually or potentially damaging to the tissue - can be thermal, mechanical or chemical
define pain perception threshold
the minimum intensity of noxious stimulation that must be reached prior to pain being felt
define pain tolerance level
the maximum amount of pain an individual can tolerate
define analgesia
less or absence of pain in response to a typically painful stimulus
define hyperalgesia
increased sensitivity and response to a painful stimulus
define hypoalgesia
decreased sensitivity to a painful stimulus
define allodynia
pain resulting from a stimulus that would not normally provoke pain
how is pain detected
nociception and nociceptors
define nociception
the process by which information is conveyed to the CNS as a result of the stimulation of specialised sensory receptors in the peripheral nervous system
what are nociceptors
free nerve endings located throughout the body which are sensitive to tissue trauma and detect potentially damaging noxious stimuli, ultimately leading to the sensation of pain
describe nociceptive pain
normal warning response to tissue damage
pain corresponds to severity of the tissue trauma
fast, rapid onset, sudden sharp pricking pain,, followed later by a dull, aching or burning pain
pain will resolve but can be recurrent
what are the 3 types of stimuli which nociceptors respond to
thermal, mechanical, chemical
what are the 3 types of nociceptors
type 1 alpha delta fibres
type 2 alpha delta fibres
C-fibres
describe type 1 alpha delta fibres
fast transmitting, small diameter, myelinated nerve fibres
respond to mechanical stimuli
rapid, sharp, localised pain
describe type 2 alpha delta fibres
fast transmitting, small diameter, myelinated nerve fibres
respond to thermal stimuli
rapid, sharp, localised pain
dorsal horn
describe C-fibres
slower, smaller, unmyelinated nerve fibres
polymodal - respond to a variety of tissue-damaging inputs (mechanical, chemical and thermal stimuli)
slow, dull, aching pain
what are the 4 phases of nociception
transduction
transmission
perception
modulation
describe the pain gate theory
there is a ‘gate’ in the brain, through which painful stimuli are allowed to pass or get blocked
the gate can either be open or closed
if open, painful signals can pass through, and be perceived by the brain to cause pain
if closed, signals will be blocked and sensation of pain will not be felt
what is peripheral sensitisation
normal protective process
lower threshold for activation
hypersensitivity to non- painful stimuli
if prolonged, can lead to abnormal pain state
what is central sensitisation
basis for chronic pain
increased sensitivity of CNS to noxious stimuli
hyperalgesia - increased pain response to normally painful stimuli
pain outlives pathology - pain percieves more tissue damage than there is
what is exercise induced hypoalgesia (EIH)
a decrease in sensitivity to painful stimuli with exercise
