PNS Review Small Group Flashcards
What is the clonidine suppression test? What might you consider if a pt fails this test?
Pt has excess NE in plasma & urine
+ Clonidine = alpha 2 agonist (autoreceptor) = ↓symp
- Would suppress NE release
Fail : worried about sympa stimulation from another source (catecholamine secreting tumor)
Which cholinergic receptors are at the atria, SA & AV nodes? What happens if you stimulate these receptors?
M2 - parasympathetic
↓HR
↓contractility (force)
Which adrenergic receptor is in the vascular smooth muscle? Effect?
Alpha 1 - sympa
Vasoconstrict
Which adrenergic receptor is at presynaptic nerve terminals? Effect?
Alpha 2 - sympa
↓NE release
Which adrenergic receptor is at myocardium, SA & AV nodes? Effects?
Beta 1 - sympa
↑HR
↑contractility
Which adrenergic receptor is at “some” vascular smooth muscle? Effects?
Beta 2 - sympa
Vasodilate
How can a pt present with ↑plasma NE causing HTN and bradycardia?
Tumor secreting NE at alpha 1
Vasoconstrict –> high BP –> slow HR
Attempt to compensate via baroreceptors - ↓HR
What are NE metabolites measured in plasma and urine?
Plasma = metanephrine & normetanephrine Urine = VMA (and MHPG)
Which enzyme in tyrosine –> NE synthesis can be targeted by drugs?
Tryosine hydroxylase
Drug = met-tyrosine
What are the reasons for combining alpha and beta receptor blockade management in pheochromocytoma?
Alpha w/o beta = pro-hemorrhagic
1st block alpha = vasodilate
2nd beta block = ↓HR
What is the triad of symptoms associated with Horner’s syndrome?
Ptosis, miosis, anhydrosis
What is Horner’s syndrome?
Loss of sympa innervation due to lesion
Why use 10% cocaine eyedrops to test?
Cocaine prevents NE re-uptake
Net ↑NE @ nerve terminals
Normal = dilation
Checking to see if nerve is releasing NE at all
Do Horner’s pts have + or - cocaine eyedrop test?
Negative - no dilation
B/c no NE release to prevent the uptake of!
Now you know something is broken, but doesn’t help you localize the lesion within the circuit
What is the rationale for 1% hydroxyamphetamine drops?
Localize lesion
↑NE release from parasympa vesicles - only need the post-ganglionic nerve to work
Pre-gang lesion = see dilation
Post-gang lesion = no change/constriction
