Autonomic II Flashcards
how is tyrosine transported into
Na dependent carrier
what is tyrosine converted to and by what?
DOPA by tyrosine hydoxylase
what is DOPA converted to and by what
Dopamine by DOPA decarboxylase
how is dopamine transported into vesicles
vesicular monoamine trasnporter
what is dopamine converted to and by what?
NA by dopamine - beta- hydroxylase
where is dopamine converted to NA
in vesicle
what is the rate limiting. step in the conversion of tyrosine to DOPA
tyrosine hydroxylase
what blocks the rate limiting step in the formation of DOPA
Alpha-methyltyrosine
what is NA released with
ATP, peptidergic cotransmitter and dopamine beta hydroxylase
what is the fusion of vesicles and NA release dependent on
Ca
how is NA inactivtaed
diffusion and uptake
what are the two uptakes for NA
uptake 1 into terminals
uptake 2 into postsynaptic cells
what can block the uptake 1 of NA
cocaine and tricyclic antidepressants
how can NA and other catecholamines be metabolized in the mitochondria of nerve terminals
in mitochondira by monoamine oxidase
what metabolizes catecholamines
catechol-o-methyl transferase
what is the shape and structure of adrenoceptors
heptahelical
G protein
what are the two types of alpha-adrenoceptors and where are they
alpha 1 (postsynaptic adrenoceptors) = vascular smooth muscle contraction and increased blood pressure
alpha 2 (mainly presynaptic) = on nerve terminals
what activates beta-adrenoceptors
NA from sympathetic postganglionic nerves and adrenaline from adrenal gland
what does each beta adrenoceptor do
beta 1 = open ca channels (heart)
beta 2 = relax vascular smooth muscle tissue, dilate bronchioles
beta 3 = on adipocytes
how do presynaptic beta receptors act
increase NA release
what are the exceptions to the rule that most visceral organs receive both parasympathetic and sympathethc innervation
spleen
kidney
liver
fat cells
and most blood vessels
what drugs can release NA from vesicles
amphetamine and tyramine
what are the generalizations of cholinergic effects
relaxation of smooth muscle and secretion
what are the generalizations of adrenergic effects
contraction and inhibition of secretion