Pharmacology Flashcards
What is an opioid?
Endogenous or synthetic substance that produces morphine life effects
What are the main groups of synthetic analogues of opiods?
- Piperidines
- Methadone-like drugs
- Benzomorphans
- Thebaine derivatives
Which receptors are responsible for most of the analgesic effects of opioids?
mu
All types of opioid receptors are what type of receptors?
Gi/Go proteins
Describe the effects of morphine
- Analgesia
- Euphoria and sedation
- Respiratory depression and suppression of cough
- Nausea/vomiting
- Pupillary construction
- Reduced GI motility
- Histamine release causing bronchoconstriction
- Hypotension
Which opioid cause physical dependance?
u-receptor agonists
What may relieve withdrawal symptoms?
Long acting u-receptor agonists such as methadone and buprenorphine
Which opioids are less likely to cause dependance?
codeine, pentazocine, buprenorphine and tramdol
Define pain
Unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage
What are the main pain receptors?
Polymodal nociceptors
Name some chemical stimuli of pain receptors
Bradykinin, protons, ATP and vanilloids
Describe the fibres of pain pathways
Mostly non-myelinated C fibres whose endings respond to thermal, mechanical and chemical stimuli
Through where do nociceptive neutrons run and where are their cell bodies?
Peripheral sensory nerves
Their cell bodies lie in the dorsal root ganglia or peripheral nerves just inside the spine
Describe the myelination of nociceptive neurones
Lightly or non-myelinated
Where do C fibres and some Aδ fibres terminate?
Laminae I and II (aka the substantia gelatinosa)
What does the substantial gelatinosa contain a lot of?
Endogenous opioid receptors
What neurotransmitters do the nociceptive afferent neurons release when they synapse in the dorsal horn?
Glutamate, substance P and ATP
Where do pain signals travel up the spinal cord?
Contralateral white matter called the spinothalamic tract
Describe some processes involved in modulation of pain transmission
Periaqueductal grey, endogenous opioid peptides
Name the 3 types of endogenous opioid peptides
- Enkephalins
- Endorphins
- Dynorphins
What is the gate control theory of pain?
Non-painful input closes the ‘gates’ to painful input, which prevents pain sensation from travelling to the CNS. Therefore, stimulation by non-noxious input is able to suppress pain
Name the different types of opioid receptors
Delta, mu, kappa receptors
What are the 2 types of cholinergic receptors?
Nicotinic nAChR and muscarinic mAChR subtypes
Describe the nAChr and where it is found
Directly coupled to caption channels and mediate fast excitatory synaptic transmission at the neuromuscular junction, autonomic ganglia and various sites in the CNS
Describe the mAChR and where they are found
- mAChRs are typical GPCRs with 5 molecular subtypes (M1-M5)
- M1,3&5 couple with Gq to activate the inositol pathway
- M2/4 act through Gi to inhibit adenylate cyclase and reduce cAMP
- mAChRs mediate acetylcholine effects at postganglioic parasympathetic synapses
Where are the different muscarinic receptors found?
M1 - neural
M2 - cardiac
M3 - glandular/smooth muscle
M4/5 - mostly CNS