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level: Level 1

Questions and Answers List

level questions: Level 1

QuestionAnswer
• important regulator of virtually all organ systems • crucial for the maintenance of blood pressure even under relatively minor situations of stress (e.g. gravitational stress of standing) • mediated by the release of NE from nerve terminals, which then activates postsynaptic sites • adrenal medulla releases Epi, in response to stimuli (stress)SYMPATHETIC NERVOUS SYSTEM
1 Epinephrine acts as __ 2 Norepinephrine acts as __1 hormone 2 neurotransmitter
Differentiate Hormones and NeurotransmittersHORMONES: 1 released by ENDOCRINE GLANDS 2 travel through blood to act on DISTANT TARGET CELLS 3 the effects are SLOWER but LONGER LASTING 4 part of the ENDOCRINE SYSTEM NEUROTRANSMITTERS: 1 released by the NERVE CELLS 2 travel across the SYNPASE to act on NEARBY CELLS 3 the effects are FAST ACT but SHORTER LASTING 4 part of NERVOUS SYSTEM
Neurotransmission at adrenergic neurons process1 Tyrosine is hydroxylated into Dihydroxyphenylalanine (DOPA) by Tyrosine Hydroxylase. It is then converted to Dopamine by Aromatic l-amino acid decarboxylase in the presynaptic neurons 2 Dopamine is transported to vesicles. Dopamine is hydroxylated to form Norepinephrine. 3 Influx of Ca2+ causes vesicle to fuse with cell membrane and undergo EXOCYTOSIS. 4 Norepinephrine binds to Post synaptic receptor 5 Norepinephrine diffuses out of synaptic space and go to systemic circulation. or turned inactive metabolite by catechol-O methyltransferase or REUPTAKE back to the Neuron 6 Methylated by COMT and oxidized by MAO
Inhibits the formation of DOPA from TyrosineMetyrosine
1 Release Stimulators: 2 Release Inhibitors1 Tyramine, Ephedrine, Amphetamine, Angiotensin II, Latrotoxin 2 Guanethidine, Guanadrel, Bretylium
The carrier system that transports DOPAMINE into the synaptic vesicle is BLOCKED by __Reserpine
Drugs that BLOCK the RELEASE of NorepinephrineGuanethidine
REUPTAKE of Norepinephrine can be inhibited by __1 Imipramine (Tricylic Antidepressant) 2 Duloxetine 3 Cocaine 4 Reboxitin (first commercially available)
1 Enzyme that degrade/metabolize Norepinephrine 2 Enzyme that Oxidizes Norepinephrine1 Catechol-O-methyltransferase (COMT) 2 Monoamine oxidases (MAO)
the principal route by which norepinephrine is removed after its release from the synaptic cleft removes 90% of released NE; other NE left may bind and activate the receptors or they may enter the bloodstream and be metabolized by COMTNorepinephrine Transporter (NET)
NE taken back to cells may be metabolized by MAO todihydroxyphenylglycol (DHPG)
drugs that mimic the actions of epinephrine or norepinephrineSympathomimetic Drugs
• Acts DIRECTLY on alpha or beta receptors • Norepinephrine and EpinephrineDirect Agonists
Actions are DEPENDENT on the release of endogenous CATECHOLAMINESIndirect Agonists
• Stimulate adrenoceptors directly and release norepinephrine • EphedrineMixed-action Agonists
Types of Receptors1 Alpha Receptors • Alpha 1 • Alpha 2 2 Beta Receptors • Beta 1 • Beta 2 • Beta 3 3 Dopamine Receptors
a drug may PREFERENTIALLY bind to one subgroup of receptors at concentrations too low to interact extensively with another subgroupReceptor Selectivity EXAMPLE: NE - Alpha 1 = Alpha 2; Beta 1 >> Beta 2 Epi - Alpha 1 = Alpha 2; Beta 1 = Beta 2
1 Alpha Receptors 2 Beta Receptors1 Epinephrine ≥ Norepinephrine >> Isoproterenol 2 Isoproterenol > Epinephrine ≥ Norepinephrine