drugs And The SNS Flashcards
What is the precursor for nadr
Tyrosine
Explain the steps of tyrosine producing nadr at the SNS post ganglionic neurone
Tyrosine —> dopa
Via tyrosine hydroxylase
Dopa —> dopamine
Via dopa decarboxylase
Dopamine —-> nadr
Via dopamine B hydroxylase
Which enzyme metabolises nadr after reuptake
Monoamine oxidase
What happens to nadr which isn’t metabolised by monoamine oxidase
Recycled back into vesicles pre synapse
What are the 5 adrenergic receptors
A1 A2 B1 B2 B3
What 3 things is A1 binding responsible for
Pupil dilation
Vasoconstriction
Brain alertness
Which adrenergic receptor is pre synaptic and why
A2
It blocks the release of NT like nadr
What are a2 receptors called if they’re on own or other pre neurone
Own- auto receptor
Other - heteroreceptor
What 2 things is B2 responsible for
Bronchodilation
Vasodilation
What does B3 do
Increase lipolysis
Which 3 adrenergic receptors can agonist adrenaline bind to eg to cause vasoconstriction or tachycardia
A1 - constriction
B1 - tachycardia
B2- bronchodilation
Why would adrenaline be used to treat anaphylactic shock
Causes increased BP if it binds to A1 or B1
A2 agonist can be used to treat high BP, why?
Because it inhibits release of nadr which stops it binding at A1 or B1 which therefore decreases BP
What would a B2 agonist help with and give example
Salbutamol
Causes bronchodilation
Helps asthma
What would a B3 agonist do
Increase metabolism via increased lipolysis
Why can A1 antagonists be used to help urinary problems
Causes vasodilation to relax the bladder
What is an issue with A1 antagonists
Causes low BP (hypotension)
What is the consequence of a B1 or B2 antagonist
B1 antagonist - causes bradycardia
B2- causes bronchoconstriction
Which false substrate can be used to block synthesis of real nadr and how
Methyl DOPA
Forms methyl dopamine via dopa dexarboxylase
Methyl dopamine forms methyl nadr via dopamine b hydroxylase
What is the effect of Monoamine oxidase inhibitors
Causes reduced nadr metabolism
More nadr available in vesicles for release
More effects like vasoconstriction at A1 or eye dilation
Apart from increase nadr, what else do MAOI do
Decrease amine metabolism in food which increases them
Increased amines causes sympathomimetic effects eg tachycardia
