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66 Cards in this Set
- Front
- Back
what does the cardiac conduction system do
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generates and transmits electrical impulse and stimulates myocardium
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what are the specialized cells that allow automaticity, excitability, and conductivity
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nodal
purkinje |
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generates electrical impulse
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automaticity
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can be stimulated
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excitability
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stimulated to send electrical impulse on
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conductivity
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what do electrical impulses stimulate
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cardiac myocytes
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what does stimulation exchange occur through
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na
k ca |
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what is phase 4
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resting phase
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inside of cell is negatively charged and outside is positive
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phase 4
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final repolarization phase
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phase 3
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what happens in phase 3
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repolarization causes sodium to move out of cell and let K move in
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AKA plateau phase
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phase 2
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when does Ca move into cell
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phase2
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sodium enters cell and K leaves causing cell to become positive inside and negative outside
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phase 0
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what must myocardial cells do before being depolarized again
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repolarize
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cell unable to respond to electrical stimulus
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absolute refractory
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when is the phase considered absolute refrac.
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phase 0-3
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a stronger than normal electrical stimulus may cause premature depolariztion
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relative refrac.
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location of Sa nod
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upper right atrium
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functions normal pacemaker as highest rate automaticity
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Sa node
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in the lower right atrium
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AV node
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what does the AV node do
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slows conduction impulse from atria to vents allowing filling
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what happens if SA node not working
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AV takes over
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short fibers below AV node leading to branches
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bundle of HIS
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what does B HIS do
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accelerates conduction velocity
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rapidly conduct impulse per right bundle branch
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bundle branches
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has 2 branches
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left side
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automaticity of 20-40bpm
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purkinje fibers
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SA node firing
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atria contract
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slows down impulse of atria to allow vents to fill and contract for good C.O
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AV node
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where does AV node send signal to speed it up and send to body
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bundle of his
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decrease in HR causes what
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increase in interval
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decrease in interval
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increase in HR
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Autonomic NS controls what
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rate of impulse
speed of conduction strength of contraction |
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para NS causes
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decrease rate
slow impulse conduction decrease contraction |
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sympa NS causes
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increase rate
increase contraction |
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direct result of directional flow of the hearts electrical impulse
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upward or downward EKG movement
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what affects waveforms on EKG
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neg and pos electrode
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above baselin
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postive
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below baseline
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negative
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what is the Pwave
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atrial depolarization
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QRS complex
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ventricle depolarization
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t wave
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ventricle repolarization
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u wave
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repolal of purkinje fibers
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pr interval t
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travel of impulse from atria through av node to purkinje system
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ST segment
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early vent repolar
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qt interval
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vent depolar and repolar
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should be at isoelectric line
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St segment
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what do the leads do on an EKG
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6 measure electrical forces in the frontal plane
6 measure in the horizontal plane |
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NSR
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60-100
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characteristics of NSR
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60-100
P---> P interval is same R--->R interval is same PR and QRS are normal follows normal conduction |
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what is sinus bradycardia
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<60 bpm
same NSR criteria |
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who usually has sinus bradycardia
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athletes
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how can one recognize sinus brady
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decrease cardiac output
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what are some things that sinus brady occur in response to
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hypoxia
hypothermia acidosis hyper/hypo kalemia hypovolemia vagal stim toxins/trauma/tamponade hypothyroidism |
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what causes vagal stim
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para symp
valsava lifting NG/OG/Endo tubes |
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Sx of sinus brady
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hypotension
pale cool skin weakness angina dizziness confusion Decreased LOC SOB |
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Tx for sinus brady
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atropine
EPI dopamine pacemaker |
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goal for tx of sinus brady
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increase HR and contractility to improve CO
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characteristics of sinus tachy
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>100bpm
NSR criteria r/t clinical cause |
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what is sinus tachy associated wth
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exercise
pain hypovolemia myocardial ischemia heart failure fever drugs (atroping/epi/dop/caff) fear |
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Sx of sinus tachy
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dizziness/hypotension d/t decreased CO
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what does decreased perfusion cause
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increased HR
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Tx for sinus tachy
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tx underlying cause
B-adrenergic blockers verapamil antipyretics analgesics |
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decrease automaticity of SA node
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verapamil
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reduces HR and myocardial O2 consumption
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B adrenergic blockers
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