B7-010 CBCL Syncope Flashcards
predominately thoracolumbar outputs
sympathetic system
predominately craniosacral outputs
parasympathetic nervous sytem
peripheral blood vessels have exclusively […] inputs
sympathetic
has long preganglionic neurons
parasympathetic
has short preganglionic neurons
sympathetic
[…] outputs most strongly drive changes in MAP
sympathetic
how does the SNS compensate for low MAP [2]
increase peripheral resistance
tachycardia
how does the PNS compensate for high MAP
bradycardia
**this effect is very limited compared to SNS effects, SNS is main driver of MAP
stimulates all preganglionic efferent autonomic fibers
ACh
stimulates most parasympathetic postganglionic and a few sympathetic postganglionic (sweat glands) fibers
ACh
neurotransmitter that stimulates postganglionic neurons in GI and erectile tissue
nitric oxide
stimulates sympathetic fibers of thermoregulatory sweat glands
ACh
stimulates most postganglionic sympathetic fibers
Norepinephrine
**excludes thermoregulatory sweat glands
epinephrine and norepinephrine are released from
adrenal glands
cotransmitter for ACh
VIP
cotransmitter for NE
neuropeptide Y
breaks ACh into choline and acetate
acetylcholinesterase
parasympathetic effects on the eye [2]
contraction of iris (miosis)
contraction of ciliary muscle (accommodation)
parasympathetic effects on cardiovascular system
bradycardia
(can reduce peripheral resistance in GI and erectile tissue ONLY via NO)
parasympathetic effects on respiratory system [2]
contract muscle of bronchial trees
stimulates secretion of fluids
(exacerbates asthma symptoms)
parasympathetic effects on GI system [2]
increase secretions
increase peristalsis
parasympathetic effects on GU system [3]
contracts detrusor muscle
relaxes trigone and spinchter
promotes voiding
rate limiting enzyme in production of NE
tyrosine hydroxylase
describe the production of NE
tyrosine –> dopa (tyrosine hydroxylase)
dopa –> dopamine (dopa decarboxylase)
dopamine –> NE (dopamine-beta-hydroxylase)
the release of NE is […] dependent
calcium
transporter that reuptakes NE from the synaptic cleft into the neuron
uptake 1
uptake 1 inhibitors [2]
cocaine
TCAs
(increase the amount and action of NE in the synapse)
sympathetic effects on cardiovascular system [3]
alpha r: increase arterial resistance
beta 2: relax venous smooth muscle
renin secretion stimulated by beta receptors
sympathetic effects on heart [2]
beta 1: increased calcium –> increases contractility
increased AV conduction
sympathetic effects on respiratory system [2]
beta: relaxes bronchial smooth muscle
alpha: contracts blood vessels of URT mucosa (relieves congestion)
sympathetic effects on GI system [3]
alpha: contraction of spinchter
beta: longitudinal smooth muscle relaxation
decreases PNS drive on enteric system
sympathetic effects on GU system [2]
alpha: contraction of bladder and urethral spinchter for urinary retention
beta: relaxation of bladder wall smooth muscles for urinary retention
apocrine sweat glands are driven by […] SNS activity
adrenergic
thermoregulatory sweat glands are driven by […] SNS activity
cholinergic
sympathetic effects on the eye [2]
alpha: mydriasis
beta: increase aqueous humor
metabolic effects of SNS
increase lipolysis, glycogenolysis, glucose release, insulin secretion
plasma glucose is typically […] during sympathetic discharge
increased
how does autonomic dysfunction cause orthostatic hypotension?
inadequate SNS contraction of vasculature in lower extremities
how does autonomic dysfunction cause bradycardia?
SNS loss
how does autonomic dysfunction cause tachycardia?
loss of PSNS
a drop in systolic of […] or in diastolic of […] is an abnormal orthostatic BP change
systolic >20
diastolic >10
(also considered abnormal if lightheaded/dizzy)
2 common causes of orthostatic hypotension
volume depletion
ANS dysfunction
increase in heart rate >30 points on standing
no drop in BP
postural orthostatic tachycardia syndrome (POTS)
most common cause of syncope
neurally-mediated reflex
“vaso-vagal”, “vaso-depressor”
medications for orthostatic hypotension [3]
flourinef
midodrine
droxidopa
Horner’s syndrome is an example of a […] condition
focal autonomic nervous system condition
causes of acute ANS dysfunction [2]
toxins
drugs
are antihistamines cholinergic or anticholinergic?
anticholinergic
hereditary causes of chronic diffuse autonomic neuropathy [2]
familial amyloid polyneuropathy (ATTR)
hereditary sensory autonomic neuropathies
acquired causes of chronic diffuse autonomic neuropathy [2]
idiopathic
neurodegenerative (parkinson’s)
secondary disorders (diabetes, amyloidosis, autoimmune)
most common amyloidosis
light chain (AL)
acquired types of amyloidosis [2]
light chain (AL)
secondary amyloidosis (AA)
amyloid deposition damages […] fibers
small, unmyelinated
hereditary amyloidosis
ATTR
light chain (AL) amyloidosis is caused by
underlying plasma cell dyscrasia
inotersen can be used to treat
ATTR (hereditary amyloidosis)
sympathetic postganglionic neurons release […] as their primary neurotransmitter
NE
what types of neurons release ACh as their primary neurotransmitter? [3]
sympathetic preganglionic neurons
parasympathetic preganglionic neurons
parasympathetic postganglionic neurons
only system with exclusive sympathetic innervation
systemic vasculature
why is it common for small fiber neuropathies to co-occur with autonomic neuropathies?
both the small fibers and postganglionic axon of the autonomic system are unmyelinated
thus, predisposed to protein deposition
best test for diagnosis of secondary amyloidosis
abdominal fat pad biopsy
elevated protein and normal WBC on lumbar puncture
AIDP
elevated protein and elevated WBC on lumbar puncture
infection
medications used to treat POTS [5]
beta blockers
fludrocortisone
ivabradine
erythropoietin
pyridostigmine
catecholamine released from the ends of sympathetic fibers
NE
chief neurotransmitter of the parasympathetic nervous system
acetylcholine
largest autonomic plexus
celiac
plexus that supplies the viscera of the pelvic cavity
hypogastric
plexus located at base of the heart
cardiac
continuation of the celiac plexus that surrounds the SMA
superior mesenteric plexus
test that measures the autonomic nerves that control sweating
QSART
grading of adrenergic impairment requires what tests [2]
valsalva maneuver
tilt test
systolic murmur can indicate
aortic stenosis
mid-systolic click can indicate
mitral stenosis
next best test for a patient with suspected structural cardiac changes
transthoracic echocardiogram
accounts for 60% of syncope cases
neurally-mediated syncope
:)
