Physiology of Pain Flashcards
pain system components
nociceptors
ascending nociceptive tract
higher centers in cns
descending pathways
excitatory transmitters
AA: glutamate, aspartate
neuropeptides: substance p, cgrp
gfs: bdnf
peptides: bradykinin
inhibitory neuropeptides
endogenous opioids (aa): enkephalin, b-endorphin
neuropeptides: gaba
gfs: glycine
a high threshold sensory receptor of the peripheral somatosensory nervous system that is capable of transducing and encoding noxious stimuli
nociceptors
t/f in nociception, pain is always implied
false, pain sensation is not necessarily implied
what are a-delta fibers
thinly myelinated faster conduction (2-30 m/sec) innervate mechano and thermoreceptors more accurate pain localization terminate laterally in lamina 1 and 5
what are c fibers
unmyelinated conduct at <2-30 m/sec innervate mechano, thermo, and sympathetic postganglionic receptors long lasting burning pain located in lamina 2
interpret and relay sensory information from the body to the brain
dorsal horn arrangement
most nociceptive inputs in the dorsal horn arrangement
I (marginal zone)
II (substantia gelatinosa)
V
neural impulses from free nerve endings of nociception are transmitted via ____ to ____ to _____
via primary afferent nerves to spinal cord/cranial nerves to the brain stem
pathway of the spinothalamic tract
dorsal horn -> cross midline in vertebral white commisure of sc -> ascend in opposite anterolateral quadrant / some ipsilateral -> project to the thalamus
arise from laminae I, II, V and synapse with fibers that project to the somatosensory cortex
lateral thalamus
from deeper laminae VI, XI to reticular formation of brainstem and midbrain to the periaqueductal gray matter and hypothalamus or directly to areas of forebrain and somatosensory cortex
medial thalamus
aspects of pain lateral thalamus vs medial thalamus
lateral: sensory and DISCRIMINATIE
medial: AFFECTIVE, autonomic reflex responses, state-of-arousal, ad emotional aspects of pain
functions of spinohypothalamic tract
coordinates pain and autonomic functions: sleep, appetite, temperature regulation, stress response
senses of cn5
receives input from ophthalmic, maxillary, and mandibular branches
senses of glossopharyngeal nerve
tactile sense, thermal sense, and pain from mucous membranes of posterior third of the tongue, tonsil, posterior pharyngeal wall, and eustachian tubes
senses of the vagus nerve
tactile sense from post. auricular skin, ext. auditory meatus, visceral sensation from pharynx, larynx, trachea, esophagus, thoracic and abdominal viscera
higher centers in cns
discriminative
affective (cingulate cortex, amygdala; integrates noxious stimuli)
memory (anterior insula)
motor control
central switching station of the brain / relaying center for incoming nociceptive stimuli
thalamus
receives innocous and noxious stimuli from all over the body including deep tissues
hypothalamus
sends signals to pituitary gland to regulate ANS and neuroendocrine response to stress and pain
hypothalamus
receives input from spinothalamic tract, thalamus, and reticular formation to project to cortex
limbic system
location of somatosensory cortex
posterior to central sulcus – for localization of pain
responses to pain
motor effects alter pain perception stimulation of natural pain relieving neurotransmitters autonomic reaction psychogenic reaction
t/f pain is both an adaptive and maladaptive sensation
true
adaptive = early warning to protect the body from tissue injury maladaptive = pathological function of the NS
t/f pain can aggravate or precipitate myocardial ischemia
true
t/f pain increases movement of the chest wall, tidal volume, frc, and vc
false, it decreases
t/f pain can impair coughing and clearing of secretions
true
t/f pain can cause ileus and urinary retention
true
t/f pain causes sodium and water excretion
false, sodium retention and water retention
t/f pain causes hypercoagulability
true
pharma review
acetaminophen: inhibits prostaglandin synthesis
morphine: opioid agonist
ketamine: nmda antagonist
local anesthetics: block Na channels
