Pain (Chapter 7) Flashcards
how can fast pain be described ?
sharp, prickling, acute, electric
how can slow pain be described ?
burning, aching, throbbing, nauseous, chronic
how is pain initiated ? where can it be found ?
initiated by free nerve endings in superficial layer of the skin
also found in internal tissues (periosteum, arterial walls, joint surfaces, falx, tentorium of the cranial vault)
explain pain in deep tissues
they dont have pain nerves, but overall pain can give the impression of pain in these areas
what is periosteum ?
the membrane that lines the outer surface of bones
what is falx
part of the dura mater of the cranium
what is the tentorium cerebelli ?
extension of dura mater separating the cerebellum from the inf portion of occ lobes
what are the 3 types of stimuli that pain is initiated by ?
mechanical, thermal, chemical
what is fast pain initiated by? which type of stimuli
mechanical and thermal
which type of stimuli initiates slow pain ?
mechanical, thermal, chemical
name seven causes of chemical pain
bradykinin serotonin histamine potassium ions acids ach proteolytic enzymes
what is pain enhanced by ? how ?
prostaglandins and substance P
they make the nerve endings more sensitive
explain the adaptation mechanism of pain receptors
they are non-adaptable
continue to deliver pain signals and may in fact lead to greater pain sensitivity called hyperalgesia
what is the correlation between pain and tissue damage?
positive
what degree celsius is when tissues start to be damaged ?
45
following tissue damage, what is the number one responsible chemical for pain ?
bradykinin
in a painful area, what will you find local increases of ?
potassium ions and proteolytic enzymes because they directly attack nerve endings due to increased ion permeability
what is ischemia ? how does it cause pain
blocked flow
causes pain through buildup of lactic acid from anaerobic metabolism + bradykinins and proteolytic enzymes
what is bradykinin ?
a small peptide that is a physiologic mediator of pain
what is the neospinothalamic tract ?
fast pain transmitted from peripheral nerves to spinal cord by small type A delta fibers
velocity of 6-30 m/s
terminates in brain stem and somatosensory cortex
what is the paleospinothalamic tract ?
slow pain transmitted to spinal cord by C fibers at 0.5-2m/s terminating in spinal cord
explain the dual system of pain
the two tracts, slow and fast, work together
initial fast response makes person react quickly
second slow response makes person respond over time to alleviate the situation
how many pain tracts are there ?
2 except 3 in higher mammals
what are 5 non-drug ways of dealing with pain ?
1- transcutaneous electrical nerve stimulation
2- manual acupressure
3- endogenous opioids (innate)
4- surgical interruption (cutting of pain nervous pathways by cordotomy in thoracic region of spinal cord) spinal cord on side opposite to pain is partially cut in anterolateral quadrant to interrupt the anterolateral sensory pathway
5- acupuncture
does acupuncture work ?
small analgesic effect, but cannot clearly be distinguished from bias
what is the idea behind acupuncture ?
penetration of skin results in release of endogenous opioids
what is a drug that treats pain called ?
analgesic
what are analgesics to treat mild pain ?
tylenol, NSAIDs, caffein mixtures (OTC)
what are analgesics to treat severe pain ?
prescription opioids
what are the three most important opioid receptors in the CNS ?
mu
kappa
delta
what do opioid receptors do ?
mediate natural analgesic effects in response to endogenous b-endorphins
how do opioid drugs work ?
inhibit synaptic transmission in CNS
also decrease substance P transmission across cleft
where is the mu opioid receptor found ?
in pre- and post-synaptic membranes of pain
explain how opiods inhibit substance P
hyperpolarization occurs, harder to get AP
need more substance P to depolarize the nociceptor
reduces conduction along afferent nociceptor
what is morphine ?
strongest opioid analgesic
decreases pain through opioid receptors and decreases perception of pain
how is morphine most effective ?
parenterally because GI absorption unreliable
what is codeine ?
metabolizes into morphine, decreasing pain through opioid receptors
what can codeine be used with ?
aspirin, acetaminophen, caffeine
what is hydrocodone ?
stronger derivative of codein
what is vicodin ?
hydrocodone acetaminophen mixture
what happens mixing hydrocodone with caffeine ?
becomes pain and sinus medication, clearing nasal passage
what is oxycodone (oxycontin)
not as strong as morphine
has controlled release
has an abuse potential
what is methadone ?
mildest type of opioid, treating cancer patients and addictions
is caffeine an analgesic ?
not by itself, but makes opioid effects last longer (synergist)
how do opioids effect cough ?
suppresses cough center in medulla , which is why codeine used in cough medicine
how do opioids affect the GI tract ?
decreased GI mobility,constipation
how do opioids affect pupils ?
myeosis (pupil constriction)
how do opioids affect peeing ?
urinary tension, feeling of wanting to pee but can’t
how do opioids make you dizzy ?
orthostatic hypotension
how do opioids change state of mind ?
a side effect could be dysphoria
what are contraindications to opioids ?
monoamine oxidase inhibitors (antidepressants)
can lead to death
what are the advantages of local anesthetics ?
do not cause loss of consciousness even with parenteral administration
how can local anesthetics lead to coma ?
CNS depression
how are local anesthetics often used ?
parenterally by infiltration anesthesia (injection at area where anesthesia is desired) or nerve block anesthesia (injection near nerves supplying a specific area)
what does the duration of anesthesia depend on ?
the lipid solubility of anesthetic, amount of blood flow at site of injection
more blood flow carries the drug away from the site quicker
what do anesthetic names end with ?
-caine
what are examples of topical anesthetics ? what are they used for
pain relief on skin surface or mucous membranes
sprays, gels, lozenges, suppositories
what is special about topical anesthetic ethyl chloride ?
effectiveness as the result of a cooling effect (like ice but much quicker)
spray on skin until skin turns white in 5 seconds
duration of response seconds to a minute
what is the only local anesthetic that is a controlled substance ?
cocaine
what is cocaine used for and how ?
topically got anesthesia of ear, nose, and throat
how is cocaine unique ?
causes constriction of local vasculature and eliminates the need for using epinephrine
absorbed by mucous membranes and has more pronounced CNS effects, stimulatory effects first and then depressant effects
how does cocaine affect HR and BP
small doses: bradycardia
big doses: tachycardia and hypertension
what are the two main groups of analgesics ?
NSAIDs/ acetaminophen
opioids
what is the main concern when prescribing opioids as analgesics ?
constipation
recommend laxatives
