Autonomic Adrenergic Physiology Flashcards
Noreprinephrine is an example of what?
Catecholamine
What is the predominant transferable chemical mediator released from postneuronal sympathetic neurons?
Norepinephrine
Norepinephrine is synthesized from what using dopamine beta hydroxylase?
Dopamine
Dopamine is synthesized from what using aromatic acid decarboxylase (AADC)?
L-Dopa
L-Dopa is synthesized from what using tyrosine hydroxylase (TH)?
Tyrosine
Almost all sympathetic postganglionics release what?
Norepinephrine
NE acts on what coupled to a second messenger system to influence target tissues?
Adrenergic receptors (alpha and beta subtypes)
Intracellular biochemical cascades, couple effects of receptor binding to cellular effects, amplification, recruitment of multiple effectors and relatively slow sustained response describes what?
Target cell response by adrenergic receptors
Do adrenoreceptors use the same pathways as muscarinic receptors?
Yes!
What type of adrenoreceptor causes smooth muscle contraction ex: vasculature, iris?
Alpha1 (a1) receptor
What G protein is used in the a1 adrenoreceptor pathway?
Gq
Gq stimulates what to form the second messenger IP3?
Phospholipase C system
What type of adrenoreceptor stimulate the heart?
Beta1 (B1)
What G protein is used in the B1 adrenoreceptor pathway?
Gs
Gs stimulates what transmembrane protein to convert ATP into the second messenger cAMP?
Adenylate cyclase
PKA induces what in the b1 adrenergic pathway?
Increased intracellular Ca+
What adrenergic receptor causes smooth muscle relaxation ex: lungs and gut?
Beta 2 (B2) receptors
cAMP has what affect on the heart via B1 receptors?
Stimulative
cAMP has what effect on smooth muscles via B2 receptors?
Inhibitory
What inhibits adenylate cyclase, found on presynaptic terminals and inhibits transmitter release?
Alpha 2 (A2) receptors
What stimulates phospholipase C and functions in the brown fat and colon?
Beta 3 (B3) receptors
Adrenergic A1 receptors contract what smooth muscle in the eye leading to pupil dilation?
Radial fibers
Sympathetics via hypogastric nerves synapse on what 2 parts of the bladder?
Fundus and trigone
What receptor contracts the bladder trigone?
A1
What receptor relaxes the bladder Fundus?
B2
What receptors regulate NE stimulation and down play overly strong input to the heart by reducing the amount of neurotransmitter (NE) released?
Alpha 2 (A2) receptors
What receptors stimulate phospholipase C
A1 and B3
What receptors stimulate adenylate cyclase?
A2,B1 and B2
Sympathetic postganglionic release what neurotransmitter to sweat glands and fibers to blood vessels in skeletal muscle?
ACh
Sympathetics utilize what type of receptors in the skin for sweat secretion?
Muscarinic receptors
Re uptake into nerve terminals, uptake at extra neural sites after diffusion out of Junctional cleft and metabolic transformation ( monoamine oxidase - MAO-A and MAO-B, Catechol-O-methyltransferase COMT) describes what?
Termination of NE action
What catecholamine released into circulation stimulates adrenergic receptors?
Epinephrine
What are analogous to post ganglionic sympathetic neurons and are specialized to release epinephrine and small amounts of NE into the blood stream?
Chromaffin cells
What sympathetic neurotransmitter acts more strongly on beta receptors?
Epinephrine
What sympathetic neurotransmitter acts more strongly on alpha receptors?
Norepinephrine
Can epinephrine act on both A and B receptors?
Yes! ( epi has some selectivity for B receptors while NE has some selectivity for A receptors)
In renal vasculature dopamine is secreted from where?
Proximal tube