LATEST UPDATE|RATED 100%CORRECT
depolarization - ANS -- inside of cell becomes positive, outside negative
- contraction
- na+ channel opens
- ELECTRICAL
repolarization - ANS -movement of cells = inside is negative again
- na+ channels close, k+ channels open
- MECHANICAL
p wave
qrs wave
t wave - ANS -- (p) atrial depolarization
- (qrs) ventricular depolarization
- (t) ventricular repolarization
refractory period - ANS -per of time where cardiac cells cannot respond to stimulus
absolute refractory period - ANS -beginning of qrs to peak of t wave
relative refractory (vulnerable per of repolarization) - ANS -- cardiac cells have repolarized enough to
respond to strong stimulus
- during this per a strong stimulus may overtake the pacemaker of the heart
- ex. PVC during vulnerable period may turn into vtach or torsades
- prolonged QT interval inc possibility
,causes of prolonged qt intervals - ANS -haldol, bradycardia, hypokalemia
automaticity - ANS -ability of pacemaker cells to initiate electrical impulse
excitability - ANS -ability of muscle cells to respond to outside stimulus
conductivity - ANS -ability to recieve electrical stimulus and conduct impulse to adjacent cells
contraction - ANS -cardiac cells shorten = muscular contraction in response to electrical stimulus
sa node - ANS -- primary pacemaker of heart
- 60-90 bpm
av node - ANS -delay = atrial contraction + ventricular filling
- 40-60 bpm
bundle of his - ANS -ability to self initiate electrical activity
- 40-60 bpm
purkinje fibers - ANS -network of fibers that carry electrical impulse to ventricular muscle cells
- 20-40 bpm
NSR
Brady
Tachy
SVT
Junctional
Ventricular rhythm - ANS -NSR 60-100
Brady 40-60
, Tachy >100
SVT >150
Junctional 40-60
Ventricular rhythm 20 - 40
PR interval - ANS -0.12-0.20
beginning of p to beginning of qrs
qrs interval - ANS -< 0.12
beginning of q to end of s
qt interval - ANS -beginning of q to end of t
- heart rate dependent
is rhythm regular or irregular - ANS -measure interval between R waves
ventricular rate - ANS -- count # of qrs complexes
atrial rate - ANS -- count # of p waves
causes of bradycardia - ANS -- vagal
- dig, beta blockers
- compensatory response in acute MI
- ischemic heart disease
- sick sinus. synd
- inc intracranial pressure
bradycardia symptoms - ANS -hypotension, AMS, signs of shock, ischemic chest discomfort, HF