L6 - principles of drug action on neurotransmission Flashcards
what do local anaesthetics do
block neurotransmission by blocking Na channels
where are ganglia in SNS
close to spinal cord
where are ganglia in PNS
closer to tisssue
where do motor neurons act
voluntary muscle
spinal cord to NMJ - skeletal muscle
where is ACh the neurotransmitter?
all of PNS
all first synapses (CNS to ganglia)
NMJ
sweat glands
where is NA the neurotransmitter
all postganglionic SNS synapses except those that innervate sweat glands
where are dopamine and serotonin neurotransmitters?
CNS
what part of spinal cord do SNS originate
thoracolumbar
what part of spinal cord do PNS originate
cranial&sacral
top&bottom
what is presynaptic autoinhibitory agonism
the NT released from presynaptic membrane also binds to receptors on presynaptic membrane to inhibit its release
in what way can NT activity be stimulated at the synapse
provide more precursor
in what ways can NT activity be inhibited at the synapse
- block precursor uptake
- inhibit enzyme cascade that produces NT from precursor
- inhibit storage of NT in vesicles
- inhibit depolarisation of pre synaptic mem
- inhibit Ca channel opening
- inhibit vesicle fusion
- displace NT from vesicle
what does neostigmine inhibit
the degradation of NT by enzymes in the cleft
what happens to NT in the cleft
- degradation by enzymes
2. reuptake into pre synaptic nerve
what are the sites of drug action at the synapse
- synthesis of NT
- storage of NT
- release of NT (vesicle fusion)
- receptors (antagonists/agonists)
- inhibition of reuptake
- inhibition of NT degrading enzymes
- inhibition of autoinhibition
