2-autonomic Flashcards
how is tyrosine transported into the adrenergic terminals
by a Na+ dependent carrier
what is tyrosine converted into what and how
into DOPA via tyrosine hydroxylase
what is the rate limiting step of making dopamine
tyrosine hydroxylase converting Tyr to DOPA
what is DOPA converted to and how
into dopamine by DOPA decarboxylase
how is dopamine transported into vesicles
vesicular monoamine transporter
what does dopamine get converted into and how
dopamine converted to noradrenaline by dopamine -β- hydroxylase
what is fusion of vesicles and NA release dependent on
Ca2+
what is NA converted into? using which enzyme?
adrenaline using phenylethanolamine N-methyltansferase
what some cotransmitters released with NE?
ATP, peptidergic co-transmitter, dopamine beta hydroxylase
what substances (other than Ca2+) are capable of releasing NE from vesicles in the synaptic terminal?
AMPHETAMINE
tyramine
what happens to NA after release and binding to receptor
- reuptake
- diffuses out of synapses into the lymphatics
what are the ways that NA can be uptaken
uptake 1- into terminals (where it was originally released)
uptake 2-into postsynaptic cells
what blocks uptake 1 of adrenergic receptors
cocaine and tricyclic antidepressants
what does cocaine and tricyclic antidepressants do
blocks uptake 1 of adrenergic receptors
what does monoamine oxidase do
metabolize noradrenaline in mitochondria of nerve terminals
what does catechol-o-methyl transferase do
metabolize the catecholamines that were taken up into liver by uptake 2
what does catechol-o-methyl transferase do
metabolize the catecholamines that were taken up into liver by uptake 2
what happens to the catecholamines that are taken up uptake 2? where does this happen?
catechol-o-methyl transferase in the liver
how are catecholamines taken up into the liver
uptake 2
what are adrenoceptors like (2 things)
heptahelical and G protein/metabotropic
NO ION CHANNELS
what kind of ion channel is coupled to adrenoceptors
NONE
what activates α-adrenergic re eptors
NA from sympathetic postganglionic nerve
where are α1 found
what do they do
postsynaptic adrenoceptors on vascular smooth muscle
where are α2 found
autoreceptors/presynaptic adrenoceptor on nerve terminals
what is the role of α2
negative feedback control (autoreceptor)
what is the role of α1
contraction and increase BP (they are on smooth muscle)
how are β-adrenoceptors activated
NA from sympathetic postganglionic nerves and adrenaline from adrenal gland
what does β1 activation do
opens Ca2+ (in heart)
what does β2 activation do
relaxes vascular smooth muscle and dilates bronchioles
where is β3
adipocytes
what do presynaptic β receptors do
increase NA release
what are the general cholinergic effects
relaxation of smooth muscle and secretion
What is the general difference between cholinergic and adrenergic effects?
the exert the opposite effect
what are the general adrenergic effects
contraction and inhibition of secretion
how would you pair -muscarinic -adrenoceptors -parasympathetic -sympathetic into pairs based on their similarities
muscarinic+parasympathetic
adrenoceptor+sympathetic
how do the effects of α-adrenoceptors and β-adrenoceptors compare
often exert opposite effects in similar tissues
what is the adrenergic effect and receptor of the heart
increased force and rate of contraction
β1
what is the adrenergic effect and receptor of the blood vessels (skin and spleen)
constriction, α1
what is the adrenergic effect and receptor of the blood vessels (skeletal muscle)
relaxation (more blood and power to muscle)
β2
what is the adrenergic effect and receptor of the lungs
relaxation of bronchiolar smooth muscle, decreased secretion
β2
what is the adrenergic effect and receptor of the intestines
relaxation
β2 α2
what is the adrenergic effect and receptor of the bladder
relaxes wall/contracts sphincter
β2 α1
what is the adrenergic effect and receptor of the eye ciliary muscle
relaxes for far vision
β2
what is the adrenergic effect and receptor of the eye/iris
contracts radial muscle (mydriasis)
α
what is the adrenergic effect and receptor of the skin, pilomotor smooth muscle
contracts (goosebumps)
α
what is the adrenergic effect and receptor of the apocrine (stress)
increases
α
what is the adrenergic effect and receptor of the fat cells
lipolysis
β3
what is the adrenergic effect and receptor of the kidney
renin release
β1
what is the cholinergic effect and receptor of the heart
decreased force and rate of contraction
M2
what is the cholinergic effect and receptor of the blood vessels (skin and spleen)
endothelium-dependent relaxation
what is the cholinergic effect and receptor of the lungs
contraction of bronchiolar smooth muscle, increased secretion
what is the cholinergic effect and receptor of the intestines
contraction and increased secretion
M3
what is the cholinergic effect and receptor of the salivary glands
increased secretion
M3
what is the cholinergic effect and receptor of the bladder
contracts wall/relaxes sphincter
M3
what is the cholinergic effect and receptor of the eye ciliary muscle
contracts for near vision
M3
what is the cholinergic effect and receptor of the eye/iris
contracts sphincter muscle (miosis)
what is autonomic tone
basal level of stimulation that visceral organs receive from both parasympathetic and sympathetic innervation
which tissues ONLY receive sympathetic innervation?
spleen, kidney, liver, fat cells, and most blood vessels
does parasympathetic or sympathetic have more autonomic tone
para
what are the main tissues under sympathetic tone
+the sympathetic role
arterioles and veins (vasoconstrict)
spleen (capsule contraction, immune response)
kidney (renin secretion)
what happens with ganglionic or adrenoceptor blockade to arterioles
vasodilation, increased peripheral blood flow, flushing, hypotension
what happens with ganglionic or adrenoceptor blockade to veins
vasodilation, pooling of blood, decreased venous return, decreased cardiac output
what is the main autonomic tone to heart and why is it beneficial
parasympathetic
-to increase HR, just remove the parasympathetic breaks–> it is easier than trying to wait for sympathetic stimulation
what determines how target tissue will respond to systemic administration of muscarinic/cholinergic or adrenergic blocking agents?
whether the tissue is under predominantly sympathetic or parasympathetic tone
what is atropine
and some side effects
muscarinic antagonist
so like constipation, tachycardia, dry mouth, urinary retention
what does α-adrenoceptor antagonist do to blood flow/vessels and why
produces vasodilation and lowers blood pressure because vessels are usually under adrenergic tone (state of constriction)
what is the baroreceptor reflex
decreased aortic BP-decreased baroreceptor activity in carotid sinus, aortic arch lungs and heart send afferent info to nucleus of solitary tract and ventrolateral medulla
causes efferent sympathetic outflow increased and decreased parasympathetic outflow from brain
this increases HR and BP via vasoconstriction
what does high aortic pressure do (baroreceptor reflex pathway)
high pressure, increases baroreceptor discharge, activation of parasympathetic outflow and reduce sympathetic outflow (low HR and vasodilate)
how is baroreceptor involved in postural reflex
standing-25% blood goes to legs
reflex triggers increased HR and constriction of vessels in veins
