Pain

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

purpose of pain

Answer 2

prevents serious injury
teaches avoidance
prevents permanent damage

Question 3

pain is classified in two ways - list those two

Answer 3

based on location and. based on duration

Question 4

two classifications of pain on location

Answer 4

somatic pain
visceral pain

Question 5

two classifications of pain based on duration

Answer 5

acute pain and chronic pain

Question 6

somatic pain

Answer 6

1. superficial pain (outside our body)
2. arises from nocieptive receptors in the skin
3. it is localized, fast or slow onset, feels like sharp burning or prickling and is constant

Question 7

visceral pain

Answer 7

poorly localized
originates from internal organs
activates nociceptors on internal organs
feels like an achy and dull sensation

Question 8

acute pain

Answer 8

short lived and adaptive pain resposne
occurs in response eto injury or illness
responds well to interventions
produces behavioural change that promotes healing.

Question 9

chronic pain

Answer 9

mismanaged acute pain turns into chornic pain
pain persists beyond the normal healing period

Question 10

pain classification based on mechanism (list 3)

Answer 10

nociceptive (acute), neuropathic (chronic), nociplastic (mix)

Question 11

nocicepetive pain - cause, subtypes, duration

Answer 11

relatex to damage or the threat of damage to non neural tissues
somatic, visceral
less than three months

Question 12

neuropathic pain - cause subtypes, duration

Answer 12

injury or disease of the peripheral or central nervous system
sensory abnormalities cause varying degrees ofpain sesnations from numbness to hypersensitivity, in which pain receptors react to non-painful stimuli. e.g. allodynia and hyperalgesia.
lasts more than three months

Question 13

nociplastic pain - cause subtypes, and dudration

Answer 13

abnormal processing in the CNS with no actual threatened tissue damage and no damage or disease of the nervous system - e.g., fibr0myalgia, IBS
non nocicepetive and non neuropahic pain.
as - associated with central sensitization or psychological disttress or ongoing inflammation.
activation and sensitization of nociceptive pain pathway by mediators released at a site.

Question 14

Modulation of Pain sensation steps (5)

Answer 14

1. nocicepetors detect harmful signal
2. Message passes from the site of injury to spinal cord through adelta and c fibers (which are the first order sneory afferents coming into the gate at the dorsal horn of hte spinal cord.
3. message is relayed to second order neurons whose fibers asccent to the thalamus
4. third order afferents project it to higher brain centers of hte limbic system, the frontal cortex, and the primary sensory cortex
5. the electrical communication between these regions gives rise to the feelling of pain.

Question 15

transduction

Answer 15

first and second order neurons, detect noxious stimuli from somatic and visceral tissue. this painful stimuli is converted to energy, and sends the impulse across peripheral nerve fibers

Question 16

transmission

Answer 16

nociceptive message is transmitted to the CNS of actual or impending tissue injury
a delta fibers send sharo, localized sensations, c fibers relay impulses that are poorly localized.

Question 17

perception

Answer 17

person is aware of the pain
somatosensory cortex identifies the location and intenisty

Question 18

modulation by body

Answer 18

excitatory transmitter mediate synaptic transmission to the dorsal horn
inhibiotry NT work to inder pain

Question 19

excitatory NT , inhibitory NT

Answer 19

E - Glut, Substance P, CGRP
I - GABA, Glycine, Enkephalins, Dynorphin, NOradreanline

Question 20

Types of NOciceptors and their functino

Answer 20

mediate potentially harmful stimuli
1. thermal receptors are activated by temperatures above 42 degrees or severe cold
2. mechanical nociceptors respond to strong pressure
3. chemically sensitive respond to various chemicals such as bradykinin, histamine, high acididty
4. polymodal ones respond to a combo

Question 21

Nociceptor activation

Answer 21

1. tissue injury releases bradykinin and prostaglandins that sensitize or activate nociceptors, which in turn release substance P and CGRP
2. Substance P acts on mast cells to cause degranulation and release histamine, which activates nociceptors
3. Substance P causes plasma extravasation and CGRP dilates blood vessels, the resulting edema causes additional release of bradykini
4. 5HT is released from platelets and activates nociceptors.

Question 22

how does thickness of a nerve fiber correlate to speed with which info transfers

Answer 22

thicker the nerve (a delta), fasater the info
slow pain - c nerve fibers

Question 23

neospiniothalamic tract transmission

Answer 23

a delta fibers takes info through the DRG, synapse onto second order neurons which carry the signal all the way to the thalamus

Question 24

paleospinothalamic tract

Answer 24

The C fibers synapse on the second order neurons which carry the signal to the reticular formation and midbrain and hten go to the thalamus.

Question 25

what happens in between the first and second order neuron?

Answer 25

first order release NT glutamate, Substance P, CGRP, NO, and PG and BDNF.
Glutamate b inds to metabotropic glutamate specific receptors and ionotropic AMPA receptors.
SP and BDNF bind to the G-protein coupled NK1 receptor and Tyrosine kinase receptor B.
Prostaglandins bind to the EP1 receptor.
THe binding of these causes a sensitized state

Question 26

in the sensitized state, the second order neuron

Answer 26

1. ligand gated ion channels like NMDA are up regulated, mg plug removed, increase in glutamate sensitivity to signalling is intensified
2. An increase in intracellular Ca concentrations leads to a potentiation in activity via AMPA receptors results in transmission of the nerve signal from second order neurons

Question 27

second order neurons are iether

Answer 27

1. nociceptive specific
2. wide dynamic range (receive non noxious afferent input as well)

Question 28

How is pain cut off

Answer 28

inhibitory pathways descending from the brainstem release NT in the spinal cord such as 5HT and NA, or activate small opioid containing interneuronsin the spinal dorsal horn to release opioid peptides. this slows down transmission - ucts down the signal to the brain.

Question 29

what does the activation of the opioid receptors lead to

Answer 29

Reduced cyclic AMP, coupled to inhibiotry G protein.
Reduces neuronal cell excitation and transmission, closesCa channels, stimulation of K+ efflux - hyperpolarization.
can lead to euphoria - involves dopaminergic pathways.

Question 30

what to opioids do

Answer 30

bind to enkaphalin receptors, mimicking the pain supressing effects of teh endogenous opiate enkephalin.

Question 31

what do enkaphalin containing interneurons normamlly do

Answer 31

synapse with the terminals of pain fibers and inhibit the release of substance P thus fewer pain impulses to the brain.