Pharmacology: Autonomic Pharmacology Flashcards
what does the ANS mediate
all output from the CNS (barr skeletal muscle)
what involuntary functions does the ANS mediate
- heartbeat
- immune system mediation
- metabolism
- all exocrine and some endocrine functions
- smooth muscle
what is the sympathetic response
- stress and energy consumption
- fight or flight
what is the parasympathetic response
- restorative and energy conserving
- rest and digest
what are the 3 divisions of the ANS
sympathetic, parasympathetic, enteric
what is always the transmitter for pre-ganglionic fibres
ACh
describe the conduction of an AP in a sympathetic neurone
- thoracolumbar outflow from CNS
- AP arrives in pre-synaptic terminal and triggers Ca2+ entry via VGICs
- ACh released by exocytosis and travels along the neurone
- ACh binds and opens LGICs in the post-ganglionic neurone
- depolarisation and AP initiation to pre-synaptic terminal where NA is released
- NA activated ADR GPCRs in effectors cells and induces a cellular response
describe the conduction of an AP in a parasympathetic neurone
- craniosacral outflow from CNS
- AP arrives in pre-synaptic terminal and triggers Ca2+ entry via VGICs
- this triggers ACh release by exocytosis and this travels along the neurone
- ACh then binds to LGICs in the post-ganglionic neurone again triggering Ca2+ entry
- depolarisation and ACh is released travelling to and binding to the M GPCRs in effector cells triggering a cellular response
neurones with ACh as an effector are called
cholinergic
neurones withe NA as an effector are called
adrenergic
what other class of transmitter is there and when is this released
non-agrenergic, non-cholinergic (NANC), usually released as a co-transmitter with ACh or NA
what are the sympathetic co-transmitters
ATP or neuropeptide Y (NPY)
what are the parasympathetic co-transmitters
vasoactive intestinal peptide (VIP) or nitric oxide (NO)
which transmitters induce a - rapid - intermediate - slow response
- ATP and ACh
- NA and NO
- NPY and VIP
ACh is an endogenous agonist to what 2 of cholinergic receptors
- muscarinic
- nicotinic
where are nicotinic receptors found and what type of receptors are they
- ganglia and neuroskeletal muscular junctions
- LGICs
where are muscarinic receptors found and what type of receptors are they
- effector cells
- GPCRs
NA and A are endogenous agonists to what 2 of adrenergic receptors
- alpha-ADR
- beta-ADR
where are adrenergic receptors found and what type of receptors are they
- in differing tissue types
- GPCRs
for alpha and beta ADR what is the order of their effectors in order of most potent to least
- alpha - NA > A > isoprenaline
- beta - isoprenaline > A > NA
describe cholinergic transmission
- choline uptake via transporter
- ACh synthesis from choline and acetyl CoA, and stored in vesicle alongside ATP and cations
- AP depolarisation
- Ca2+ influx and Ca2+ induced release of ACh via exocytosis
- muscarinic/nicotinc receptor activation and cellular response
- degradation, reuptake and reuse
describe the formation of a nicotinic receptor
5 subunits form a central cation channel
what are nicotinic receptor subtypes
- ganglionic, skeletal muscles in the PNS
- alpha subtypes in CNS
describe cholinergic transmission at ganglia
- ACh binds opening Na+ channels
- depoarisation causes further Na+ influx
- AP generated
describe parasympathetic cholinergic transmission
- choline uptake via transporter
- ACh synthesis from choline and acetyl CoA, and stored in vesicle alongside ATP and cations
- AP depolarisation
- Ca2+ influx and Ca2+ induced release of ACh via exocytosis
- muscarinic receptor activation and cellular response
- degradation and reuptake
what do M1 receptors do
stimulate PLC
- increase gastric acid secretion
what do M2 receptors do
inhibit adenyl cyclase and open K+ channles
- decrease HR
what do M3 receptors do
stimulate PLC
- increase salivary secretion, visceral SM contraction in lungs and indirect relaxation of vascular SM (NO)
describe NA transmission
- NA synthesised and stored
- AP depolarisation
- Ca2+ influx via voltage-gated Ca2+ channels stimulates NA release
- ADR stimulation and cellular response
- NA reuptake via transporters and NA metabolism
what do beta1 receptors do and what is there G protein
stimulate adenyl cyclase, Gs
- increase HR and force of contraction
what do beta2 receptors do and what is there G protein
stimulate adenyl cyclase, Gs
- bronchial and vascular relaxation
what do alpha1 receptors do and what is there G protein
PLC stimulation, Gq
- vascular SM contraction
what do alphaw receptors do and what is there G protein
inhibit adenyl cyclase, Gi
- inhibition of NA release
describe the -ve feedback loop of pre-synaptic receptors and transmitter release
- stimulation by agonist would decrease transmitter release
- inhibition by antagonist would increase transmitter release
