SDRB- pain and pain suppression

what do nociceptors detect?

pain

what are on the end of nociceptors?

free nerve endings

what are free nerve endings responsible for?

pain

what molecules are made as a part of inflammatory response?

prostaglandins

what do prostaglandins do?

sensitise the free nerve endings and make fire potentials more likely to fire to the CNS

what about A[delta] fibres on nocireceptors make them responsible for early pain?

they are highly myelinated axons

what type of nocireceptors are informative about location?

A delta fibres

what about C fibres make them convey pain slower?

they are unmyelinated

what are the 2 types of C fibres

some are dorsalsensitive to pungent irritants and some are sensitive to extremes of temperature, acid and capsaicin

where does the nociceptors cell body reside?

in the dorsal root ganglion

where does the nociceptor make a synapse?

onto the dorsal horneuron in the spinal cord

what is released in the synapse in the dorsal horneuron in the spinal cord that makes pain more intense?

substance P alongside glutamate

where does the long axon of the dorsal horneuron run to?

the thalamusw

where does the thalamic neuron make synapses to?

the primary somatosensory cortex

what is the name of the structure in the pirmary somatosensory cortex that tells us where in the body a sensation is?

homunculus

what are the 2 brain areas associated with the dual brain mechanism of pain?

primary somatosensory cortex and the anterior cingulate cortex

what brain area is more associated with the emotional side of pain?

anterior cingulate cortex

what study demonstrated that pain tolerance resides in the anterior cingulate cortex?

hyponosis-induced analgesia study

what mechanism reduces pain by inhibiting the pain signal from entering the CNS at the first synapse?

descending analgesia circuit

what brain area, when artificially stimulated, suppresses pain signals coming in?

peri-aquaductal grey

what things naturally activate the peri-aquaductal grey?

stress and the placebo effect

what drug do they use to test whether a mechanism uses the DAC?

naloxone

what is naloxone?

an opiate receptor blocker

what substance is typically used topically on the skin for muscle pain?

capsaicin

how does capsaicin provide local anesthesia?

depletes sensory neuron terminals of substance P

where do non-steroidal anti-inflammatory drugs (NSAIDS) work in the body?

peripherally

what do NSAIDS inhibit?

cyclo-oxygenase 1 and 2

what does the inhibition of COX-1 and COX-2 do?

reduces the production of prostaglandins

what does paracetemol produce when it reacts with endogenous molecules?

AM404

what is AM404 an agonist of?

TRPV1 and CB-1 cannibinoid receptors

where are TRPV1 receptors found?

nociceptors

where are CB-1 receptors found?

many central and peripheral pain related circuits, including the DAC

what is the natural source of opiates

the opium poppy

how is opium usually ingested

smoked or eaten

how is codeine usually ingested?

typically oral as a cough suppressant

how is heroin usually ingested

injection

how is oxycodone usually ingested

pills

what is the physiological action of opiates

mimics endogenous opioids

what receptors to opioids bind to?

endogenous opioid receptorsw

what are the 3 major subtypes of opioid receptors?

delta, kappa and mu

what and where do opioid drugs inhibit?

inhibitory neurons in the periaqueductal gray matter in the midbrain

what system causes the addictiveness of opioids?

Mesotelencephalic dopamine system`

what happens in the ventral tegmental area that causes opioid addictiveness?

opiates inhibit GABA-ergic interneurons, releasing inhibition from neurons

what is the result of opiates inhibiting GABA-ergic interneurons?

more dopamine is released

What is easy for THC and CBD to cross?

the blood-brain barrier as they are very lipid soluble

what is the half life of THC and CBD?

7 days

what is the physiological action of THC?

partial agonist on CB1 and CB2 receptors

what is the main responsibility of THC?

psychedelic effects

What is the physiological action of CBD?

antagonist on CB1 receptors

what are the endogenous ligands of cannabinoid receptors?

anandamide and 2-AG

where is the highest concentration of cannabinoid receptors?

the hippocampus

what is the hippocampus mainly responsible for?

memory

where are the endocannabinoids released from?

the postsynaptic side of a stimulated synapse

what do endocannabinoids suppress?

the presynaptic release of neurotransmitters

what does the endocannabinoids suppression of presynaptic neurotransmitters do in the hippocampus?

this affects GABA, suppressing inhibition

what is the name for the suppression of inhibition by cannabinoids?

Depolarization-induced suppression of inhibition