Unit 2 Flashcards
What is pain
An unpleasant sensation caused by a noxious stimulant to a nerve, mediated and interpreted by the brain
What are sensory receptors
Nociceptors are found in every tissue except the brain. they respond to sever stimuli such a s thermal, mechanical (blood flow changes to organs), and the presence of chemical substances (bradykinin, serotonin, histamine, K+, PGs and substance P)
Describe the Theories on the Nature of Pain
it is an idea that pain can be controlled through modulation. We are able to reduce excitation or increase inhibition.
What is pain threshold?
the point at which a sensation starts to be painful and discomfort results (varies)
Define pain perception
it is an anatomical process
it is similar in most healthy people
transmission to CNS
LA blocks pain perception
Define pain reaction
an individuals manifestation of perceived pain
GA blocks this
pain is personal and subjective
What are some methods of inducing local anaesthetia
- compression of tissue
- low temperature
- anoxia
- chemical irritants
- neurolytic agents such as alcohol or phenol
- chemical agents such as local anesthetics
What are the different types of pain?
- Neurogenic: sharp, intense (CTS) - tooth pain
- Vascular: diffuse (perio, sinuses)
- Muscular: dull ache (TMJ)
* these can be diagnostic, as described by client
List factors affecting the Pain Reaction Threshold
- fear and apprehension
- gender
- fatigue
- emotional stress
- age (increased with young and decreased with old) - able to control emotions better
- race
What is a neuron
an excitable cell
What is a nerve
bundles of axons
occur in the PNS
What is endoneurium
connective tissue
wraps the axons
What is fascicles
bundles of nerve fibers
What is the perineurium
connective tissue
wraps the endoneurium/fascicles
What is the epineurium
connective tissue
fills the space inside (deep) superficial wraps the nerve
What are the mantle bundles
bundles of nerves around the outside
What are the core bundles?
bundles in the middle
what is an axon
long slender projections of neurons, nerve fibers
What are tracts
equivalent to nerve in the CNS
What increases pain threshold
sleep rest diversion empathy specific medications such as analgesics, antianxiety agents and antidperessants
What decreases pain threshold
anxiety sleeplessness tiredness anger fear, fright depression discomfort pain isolation
What is the theories on Nature of Pain
- although at the time less was known about electrophysiolocial, anatomical, neurochemical nature of pain, the concepts of convergence and modulation led to the idea that pain could be controlled through modulation - reducing excitation or increase inhibition
- gating mechanism within the dorsal horn of the spinal cord closed in response to normal stimulation of fast conducting “touch” nerve fibers….but opened when the slow conducting fibers transmitted a high volume and intensity of sensory signals
- psychological factors play a role in the perception of pain
- important when providing LA to clients. Voice modulation….talk smoothly, and gain trust will help block gate
What is the CNS
brain, spinal cord
-receives sensory information, processing information, initiates a response
What is the PNS
peripheral nervous system; nerve tissues that lie in the periphery of outer regions
- 31 pairs of spinal nerves
- 12 pairs of cranial nerves
What is afferent
incoming information traveling along sensory or afferent pathways
What is efferent
outgoing information doing motor or efferent pathways
What is the somatic nervous system
- subdivision of efferent of teh PNS
- controls the body’s voluntary and reflex activities (somatic sensory components & somatic motor components)
- external sense organs are receptors( skin)
- somatic effectors are skeletal muscles and gland cells
What is the autonomic nervous system
- carry information to the autonomic, or visceral, effectors that control involuntary smooth muscle, cardiac muscle, or glandular tissue, and other involuntary tissue
- motor component controls smooth muscle contraction of viscera and blood vessels and the secretion of glands
- further divided into sympathetic (fight or flight response) and parasympathetic (rest or digest response)
Describe sensory neurons
- peripheral free nerve endings, nociceptors
- membranes made up of proteins (channels, carriers or pumps)
- protein channels allow free movement of Ca, K, Na ions
- Lipids (oriented so hydrophilic ends face out)
- myelinated nerves have gaps called the Nodes of Ranvier
How are nerve fibers classified?
- myelinated (75% lipid, 20% protein, 5% carbohydrate)
- non myelinated
- A fibers: largest (motor or sensory), myelinated
- C fibers: numerous and small, lots in the mouth, usually unmyelinated response for “dull aching pain” - stimulus travels at 2 meters/second (pain is conducted slowly)
What makes up A Fibers
Alpha: fastest muscle movement and light touch
Beta: proprioception - impulse (vibration) are conducted rapidly along these thick myelinated fibers at 75 meters/second
Gama: touch and pressure
Delta: pain and temperature “sharp pain”
What are the stages of action potential?
- stimulus-gated Na+ channels open
- Voltage-gated Na+ channels open
- Voltage-gated Na+ channels close
- Voltage-gated K+ channels open
- Voltage-gated K+ channels close
What is absolute refractory
second action potential cannot be initiated
What is relative refractory
Interval immediately following absolute refractory period during which a second action potential is inhibited but not impossible if a larger stimulus is applied
Where are the core bundles within a peripheral trunk nerve
in the middle
Where are the mantle bundles within a peripheral trunk nerve located
surrounding areas
Which bundle of nerves would become anesthetized first?
mantle nerves
What are some of the connective tissue components of a peripheral trunk nerve?
- perineurium
- endoneurium
- epineurium
What happens when pain and vibration stimuli happen at the same time
the impulse conduction reach the brain first - releasing inhibitory interneurons therefore closing the gate and blocking sensation of pain by preventing the activation of projection neurons in the dorsal horn of the spinal nerve
What happens when pain and vibration stimuli happen at the same time
the impulse conduction reach the brain first - releasing inhibitory interneurons therefore closing the gate and blocking sensation of pain by preventing the activation of projection neurons in the dorsal horn of the spinal nerve
What type of nerve does LA work on?
non-myelin nodes
How does a stimulus create nerve impulse transmission?
- initially Ca+ channels open
- once threshold is achieved Na channels open
- depolarization during the action potential causes adjacent voltage-gated Na+ channels to open
What does the term “state dependent blockade” mean?
when neurons are in an activated state, the LA agent binds more easily
How does LA work
Could work by
- altering the resting potential of the nerve
- altering the threshold potential (when rapid firing occurs)
- decreases rate of depoloraization (primary effect of LA)
- prolonging the rate of repolarization
What is the mechanism of LA action
- LA that is lipid soluble penetrates and enlarges the membrane squeezing the Na+ channels preventing Na+ movement
- when neurons are in an activated state, the LA agent binds more easily called state dependent blockade
- LA binds to Na+channels
- note: important to block a sequence of Nodes of Ranvier to prevent skipping of an impulse
What are the stages of LA
-displacement of calcium ions from the sodium channel reception
-binding of LA to receptor site
-blockade of sodium channel
-decrease in sodium conductance
depression in rae of depolarization
What are the stages of LA
-displacement of calcium ions from the sodium channel reception
-binding of LA to receptor site
-blockade of sodium channel
-decrease in sodium conductance
depression in rate of depolarization
-failure to achieve threshold
-no propagation of action potential blockade
