pain- system

Question 1

What is pain?

Answer 1

an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage

Question 2

What is acute (nociceptive) pain?

Answer 2

normal pain
only elicited when intense/noxious stimuli threaten to damage normal tissue- induced

Question 3

Why is acute pain biologically useful?

Answer 3

serves a protective function- characterised by a high threshold and limited duration

Question 4

What axons are related to acute pain?

Answer 4

C and Adelta

Question 5

What are A delta axons responsible for in regards to pain?

Answer 5

first pain- sharp stabbing

Question 6

What are C axons responsible for in regards to pain?

Answer 6

second pain- dull aching pain
polymodal

Question 7

what are features of nociceptor endings?

Answer 7

free nerve endings, high threshold of activation, respond to intense stimuli usually associated with pain
display sensitisation
carry several types of receptor proteins

Question 8

describe a somatic nociception pathway

Answer 8

neuron 1 passes neuron 2 which crosses midline in neuron 3

Question 9

what does a stimuli pass through on its way to the thalamus in spinothalamic pathway?

Answer 9

primary afferent– medulla– pons—- midbrain—-thalamus

Question 10

where does the afferent form branches in the spinothalamic pathway?

Answer 10

Midbrain, Pons, Medulla

Question 11

overview of pain pathways for somatic?

Answer 11

receptors- nociceptors- free nerve endings
axon class- Adelta and Cfibres
CNS relay cells- spinal dorsal horn, spinal trigeminal nucleus
CNS pathway- spinothalamic, anterior (ventral)
Forebrain- Primary sensory cortex, subcortical areas

Question 12

What are good attributes in regards to pain in diagnosis?

Answer 12

location- potentially misleading
pain quality- sharp stabbing, dull ache
pain intensity
frequency/ duration
provoking/ revieling events

Question 13

What is meant by referred pain?

Answer 13

these are perceived in one part of the body, but the pathology is elsewhere, pain tends to refer from an internal organ to a superficial area e.g. skin

Question 14

With referred pain what is the referral due to?

Answer 14

due to convergence of inputs in the CNS

Question 15

what are 1-physcological factors 2-situational factors 3-emotional factors that can influence pain?

Answer 15

1- sex, age, cognitive level, previous pain, family culture
2-expectation, control, relevance
3- fear, anger, frustration

Question 16

do we have inbuilt mechanisms to help us deal with pain?

Answer 16

yes

Question 17

Describe the Gate Control Theory of Pain

Answer 17

C-fibres into dorsal horn of spinal chord where they activate second order neuron which leads to conduction of info along spinalthalamic tract which leads to pain- when we recieve this we may which to rub affected area- this causes Abeta fibres activation as they project into spinal chord they branch they send a signal up to DC-ML.
The branch that comes off activates inhibitory interneurons that inhibit the second order pain projecting neurons- this blocks tranduction to sensory cortex and loose perception of pain.

Question 18

What do the branches that come off at the Midbrain, Pons and medulla do to help reduce pain?

Answer 18

send neurons back down the spinal cord to help influence the perception of pain within the dorsal horn- modulate perception of pain- still makes us aware of pain though

Question 19

describe the descending modulation of nociceptive input

Answer 19

supraspinal loop contribution to the intrinsic modulation of nociceptive afferent input
serotonergic and noradrenergic descending projections from the PAG and medullary raphe have direct inhibition and projection neurons and/or activation of interneurons reducing activity of nociceptive circuits

Question 20

what is the 5 symptoms of mild tissue damage?

Answer 20

Heat, redness, swelling, pain, loss of function

Question 21

what is an example of triple response?

Answer 21

Dermatographia- can write on skin

Question 22

Describe the process of triple response?

Answer 22

recieve mechanical trauma to skin causing release of potassium ions and prostaglandins.
can go centrally or can release peptides from other free nerve endings (cgrp)
This can cause activation of mast cells can degranulate and cause release of histamine and react to further activate free nerve endings
They can also have affect on local capillaries- plasma extravasation- wheel around red reaction.