drugs acting on the sympathetic nervous system Flashcards
what are the 3 functional divisions of the nervous system
somatic, autonomic and enteric
whats an example of a cranial nerve
alfactory nerve (1)
optic nerve (2)
occular motor (3)
vagous nerve (10)
what does the autonomic nervous system control
cardiac muscles, glands, smooth muscles
involuntary
-(controls visceral targets to promote homeostasis)
what does the enteric nervous system
gut nervous system
what does parinteral mean in drug administration
avoids the gut
what is the name of visceral receptors
interoreceptors
how do signals travel from the stimulus to the CNS
travels from visceral receptors which transmits the information to the CNS which is then transmitted down visceral effectors via autonomic efferent fibres
what neurotransmitter is always present in the somatic nervous system
ACh - acetyl choline (which are released at neuro muscular junctions)
how many motor neurons are present in the somatic nervous systems efferent pathway
one
how many neurons are present in the autonomic nervous systems efferent pathway
two
what neuro transmitter is present during the autonomic nervous system reflexes
ACh (Acetyl choline) or NA from post-ganglionic fibres
what effects on the body does the sympathetic nervus system have once activated
- increased heart rate
- decrease in digestion
- increased blood pressure
- pupil contraction
what effects on the body does the para-sympathetic nervus system have once activated
-decreased heart rate
-increased digestion
-decreased blood pressure
-pupil dilation
why type of isotropic effect does the parasympathetic nervous system have
negative
why type of isotropic effect does the sympathetic nervous system have
positive
how does the activation of the sympathetic nervous system effect the blood vessels
- skeletal muscles dilate
- skin contracts
- viscera contracts
- salivary glands constrict
how does the activation of the para sympathetic nervous system effect the blood vessels
- skin slightly dilates
- viscera dilates
- salivary glands dilate
how does the activation of the sympathetic nervous system effect the gastrointestinal tract
- motility is inhibited
- sphincters contract
- secretions are inhibited
- liver glycogenolysis
how does the activation of the para sympathetic nervous system effect the gastrointestinal tract
- motility is stimulated
- sphincters relax
- secretions are stimulated
what is dual intervention
when a single target may receive inputs from both sympathetic and parasympathetic fibres
what type of outflow is the sympathetic nervous system
thoracolumbar
what areas of the spinal chord are activated by the sympathetic nervous system
the thorasic and the lumbar
what type of outflow is the para sympathetic nervous system
craniosacral
what areas of the spinal chord are activated by the para sympathetic nervous system
sacral
what does NA stand for
Nora adrenaline
what does NE stand for
noraepinephrine
what does cortex mean
on the outside like a bark
what does medulla mean
on the inside
what is the order of long and short neurons in the para sympathetic nervous system
pre long then post short
what is the order of long and short neurons in the sympathetic nervous system
pre short and post long
in the sympathetic nervous system Alpha 1 and Beta 1 receptors cause what type of effect
excitation
in the sympathetic nervous system Alpha 2 and Beta 2 cause what type of effect
inhibition
is the sympathetic nervous system slowly or rapidly inactivated
slowly
is the para sympathetic nervous system slowly or rapidly inactivated
rapidly
what are off-target effects
when a drug has an effect on an area of the body not intended
what’s an example of off target drug use
noradrenaline isn’t just used in sympathetic pathways but also as a neurotransmitter in the brain, so some drugs that act on adrenergic nerve terminals produce central effects (cocaine is an example of this)
where are alpha 1 receptors located and what actions are mediated there
- peripheral blood vessels (vasoconstriction)
- the prostate (contraction)
where are alpha 2 receptors located and what actions are mediated there
- presynaptic nerve terminals (inhibition of NA release)
where are beta 1 receptors located and what actions are mediated there
- heart (increase in heart rate and force of contraction)
where are beta 2 receptors located and what actions are mediated there
- peripheral blood vessels (vasodilation)
- bronchioles (bronchodialation)
what G protein is linked to alpha 1 receptors
Gq
what G protein is linked to alpha 2 receptors
Gi
what G protein is linked to beta 1 receptors
Gs
what G protein is linked to beta 2 receptors
Gs
what does the G coupling of alpha 1 with Gq activate and what does that cause
phospholipase C that converts PIP2 into IP3 and DAG.
IP3 –> Ca2+ cause smooth muscle contractions
what does the G coupling of alpha 2 with Gi activate and what does that cause
adenylate cyclase which converts ATP to cAMP which causes the inhibition of transmitter release and smooth muscle contractions
what does the G coupling of beta 1 with Gs activate and what does that cause
adenylate cyclase that converts ATP into cAMP which caused cardiac muscles to contract
what does the G coupling of beta 2 with Gs activate and what does that cause
adenylate cyclase converts ATP into cAMP which causes relaxations in smooth muscles
how directly acting drugs work
mimic or block the effect of NA by acting on an Alpha or beta receptor
- mainly acts postsynaptically
how do indirectly acting drugs work
increase or decrease NA availability by non receptor mechanisms
- mainly acts presynaptically (e.g. beta blockers)
