Opioids Flashcards
What is the pain gate?
Bw stimulus and before it enters spinal cord
What is analgesia?
Reduction or elimination of pain
What is anesthesia?
Analgesia +
What nerves innervate the cervix?
Nerves entering the spinal cord T10 to L1
What nerves innervate the uterus?
Sacral 2 - 4 parasympathetic
(Pushing stage)
What would you numb to numb the uterus and cervix?
T10-L1
What is the pain pathway?
Site of injury –> Spinal cord –> Brain stem –> Cerebrum
What is the ascending pain pathway?
Initation –> tramsission –> Perception –> reaction
What is the descending pain pathway?
Perception of pain resulting in increased inhibitory signaling from supraspinal sites such as the periaqueductal gray down to the spinal cord, and release of
endorphins/enkephalins/dynorphins from the inhibitory spinal interneurones.
Transmission through the inhibitory pathways is facilitated by noradrenaline and serotonin.
How are peripheral nocioreceptors activated (2)?
1) Directly from trauma
VIA neurotransmitter release from injured cells (PGE2, 5HT, NGF) and blood vessels (bradykins)
What is the MOA of nocioreceptors?
Nocioceptors are specialized primary sensory neurons located in the periphery that transmit sensations of injury: thermal, mechanical, chemical, into the spinal cord. The noxious stimulus is converted into an action potential and then transmitted via the C and A-d nerve fibres whose cell bodies reside in the dorsal root ganglia of the spinal cord. After synapsing in the dorsal horn, the afferent sensory information ascends the spinal cord into the mid-brain and cortex, typically synapsing at 1-2 more locations. At each synapse, the arrival of the neural impulse results in release of various neurotransmitters, notably glutamate and substance-P, which then bind to post-synaptic receptors and hence transmission of a new action potential.
What is the difference bw visceral and somatic pain?
Visceral = organs/poorly localized, referred
Somatic - bodyservice/musculoskeletal
Both mechanisms are the same
How are different pain info transmits to brain?
A-beta= fast - neospinothalamic, intense, sharp, localized and withdrawal reflexes
C=slow - paleospinothalamic , dull, burning, discomfort, autonomic reflexes, pain memory
What are the classifications of opiods (3)?
Agonist, antagonist (nalaxone), agonist-antagonist
What is the MOA of opioid action?
All opiods work in the same way.
Bind to G receptors in your brain and spinal cord and result in the inhibition of exhitatory neural transmission (AKA PAIN information) and trigger the release of dopamine.
1) Presynaptic – close voltage gated Ca++ channels – reduce neurotransmitter release (subtance P = pain)
2) Postsynaptic – enhance K+ efflux – hyperpolarize membrane and inhibit AP – reduce neural traffic
