Pain: physiology Flashcards
What is pain?
A sensory or emotional experience assoicated with damage
Is pain a sensation or perception?
Perception
What are different classes of pain?
Somatogenic, Neuropathic, pyschogenic
What is somatogenic pain?
Pain that originates from a physically identifiable cause
What is neuropathic pain?
Pain associated with nerve damage
What is pyschogenic pain?
Pain where there is no physical identifiable cause.
CAN BE AS INTENSE AS PHYSICAL PAIN
What schedules of pain are there?
Acute: short lived and remitting
Chronic: Long loved and peristant
What is Nociception?
Sensing pain from a noxious stimuli
What is a nociceptor?
A receptor which detects damage
What is a noxious stimuli?
Harmful/ unpleasant signal which activates nociceptors e.g. cold/heat extremities, chemicals
Why do we feel pain?
- Learning mechanism to avoid harmful stimulis in future
- protective distraction
- evolutionary advantage
- Protection of body parts being repaired after injury
What is pain threshold?
The level of noxious stimuli required to alert an individual of a potential threat to tissues
Pain tolerance
Amount of pain a person is willing to or able to withstand
What is accomidation phenomenom
Adapation by sensory receptors to various stimuli over a period of time often leading to reduced sensitivity
What is proprioception?
Sensory system for awareness of the position of your body. E.g. how stretched muscles are.
How do Nocioceptors detect noxious stimulis?
There are specialist ion channels and receptors on different nocicoceptors which detect changes in temperature,chemical signals associated with pain.
- Explain what happens to the graph when an injury occurs.
- What is hyperalagesia?
- What is alllodynia?
- Line shifts to left therefore less stimuli is required for same painful response
- Increased sensitivity to pain
- Pain from a non-noxious stimuli
What is the difference between anaesthesia and analgesia?
Anaesthesia: complete loss of sensation in part ot all of body casued by a neurological change or pharmacological agent
Analgesia: A neurologic or pharmacologic state in which painful stimuli are no longer painful
Describe the differences between fast pain pathways and slow pain pathways
FAST PAIN PATHWAY
SLOW PAIN PATHWAY
Carried by Ad fibres
Carried by C fibres
Sharp prickling sensation
Dull, aching burning sensation
Easily localised
Poorly localised
Occurs first
Occurs second, lasts longer, more unpleasant
Stim. of mechanical, thermal nociceptors
Stim. of polymodal nociceptors
Describe how pain is detected and responded too
Pain detected by nocicoceptors and an impulse produced which passes along sensory afferent neurons to the spinal cord. Here it passed across a synapse and is propagated up to the the thalamus. Before it may pass through reticular formation in the brain stem. At the thalamus it passes 2 further synapses before reaching the somatosensory cerebral coretx.
impules proragtes along motor neuron axon to effect muscle to have its effect.
Receptors maybe activated through immune factors released due to damaged tissues
What are the 3 theroies for pain control?
- Gate Control Theory
- Centeral biasing theory
- Endogenous opiates theory
In Gate Control theory what does the opening/ closing of the gate depend on?
- Amount of activity
- Type of nerve fibre
- Selective cognitive process
What is gate control theory?
Other sensory inputs have the ability to reduce intensity of pain by competing with neurons carrying pain impulses to reach the gate first.
Pain fibres are carried on slower, smaller neuron fibres, where as other sensations are carried by larger, faster fibres. These other sensation impules are likely to reach the gate first and inhibit the pain impulse.
What is general visceral afferent?
The general visceral afferent (GVA) fibers conduct sensory impulses (usually pain or reflex sensations) from the internal organs, glands, and blood vessels to the central nervous system.
What is the phantom limb pain?
Pathological pain after amputation felt in missing limb
What is empathy
The ability to recoginize emotions being experienced by another
What are mirror neurons?
These fire when we carry out a task and we see someone else carry out the same task
What is the central biasing theory?
The body uses past experiences with pain to judge the intensity/severity of current pain
