Latest Updated 2025/2026 Graded A+.
repolarization - answer-movement of cells = inside is negative againb b b b b b b b b b
- na+ channels close, k+ channels open
b b b b b b b
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bMECHANICAL
p wave qrs wave t wave - answer-- (p) atrial
b b b b b b b b
depolarization
b b
- (qrs) ventricular depolarization
b b b b
- (t) ventricular repolarization
b b b
refractory period - answer-per of time where cardiac cells cannot respond to stimulus
b b b b b b b b b b b b
absolute refractory period - answer-beginning of qrs to peak of t wave
b b b b b b b b b b b
depolarization - answer-- inside of cell becomes positive, outside negative
b b b b b b b b b b
- contraction
b
- na+ channel opens
b b b b
- ELECTRICAL
b
relative refractory (vulnerable per of repolarization) - answer-- cardiac cells have
b b b b b b b b b b
brepolarized enough to respond to strong stimulus b b b b b b b
- during this per a strong stimulus may overtake the pacemaker of the heart
b b b b b b b b b b b b b b
- ex. PVC during vulnerable period may turn into vtach or torsades
b b b b b b b b b b b b
- prolonged QT interval inc possibility
b b b b b
contraction - answer-cardiac cells shorten = muscular contraction in response to
b b b b b b b b b b
electrical stimulus
b b
sa node - answer-- primary pacemaker of heart
b b b b b b b b
- 60-90 bpm
b b
av node - answer-delay = atrial contraction + ventricular filling
b b b b b b b b b b
- 40-60 bpm
b b
bundle of his - answer-ability to self initiate electrical activity
b b b b b b b b b b
, - 40-60 bpm
b b
purkinje fibers - answer-network of fibers that carry electrical impulse to ventricular
b b b b b b b b b b b
bmuscle cells b b
- 20-40 bpm
b b
NSR b
Brady b
Tach y
SVT b
Junctional b
Ventricular rhythm - answer-NSR 60-100 b b b b
Brady 40-60 b
Tachy >100 b
SVT >150 b
Junctional 40-60 b
Ventricular rhythm 20 - 40 b b b b
PR interval - answer-0.12-0.20
b b b
beginning of p to beginning of qrs b b b b b b
causes of prolonged qt intervals - answer-haldol, bradycardia, hypokalemia
b b b b b b b b
automaticity - answer-ability of pacemaker cells to initiate electrical impulse
b b b b b b b b b
excitability - answer-ability of muscle cells to respond to outside stimulus
b b b b b b b b b b
conductivity - answer-ability to recieve electrical stimulus and conduct impulse to
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adjacent cells
b b
qrs interval - answer-< 0.12
b b b b
beginning of q to end of s b b b b b b
qt interval - answer-beginning of q to end of t
b b b b b b b b b b
- heart rate dependen t
b b b is rhythm regular or irregular - answer-
b b b b b b
measure interval between R waves
b b b b
ventricular rate - answer-- count # of qrs complexes
b b b b b b b b
atrial rate - answer-- count # of p waves
b b b b b b b b
causes of bradycardia - answer-- vagal
b b b b b b
- dig, beta blockers
b b b b
- compensatory response in acute MI
b b b b b b