The Heart Flashcards
(100 cards)
what is the order of the conduction system
- SA node -> AV node -> bundle of his -> Purkinje fibers
what happens in phase 0 of cardiac AP
- rapid depolarization
- Na+ channels open
what happens in phase 1 of cardiac AP
- partial repolarization
- Na+ channels close
what happens in phase 2 of cardiac AP
- plateau
- Ca2+ channels open
what happens during phasse 3 of cardiac AP
- repolarization
- Ca2+ channels close
- K+ channels open
what happens in phase 4 of cardiac AP
- pacemaker/resting
- degradation of membrane potential slowly- Ca2+ channels
whatis the absoluate refractory period
cannot be stimulated
what is the relative refractory period
- below the threshold
- respond to greater than normal stimulus
what are the 3 types of refractory period
- absolute refractory period
- relative refractory period
- supernormal excitatory period
what happens during the P wave
atrial depolarization
what happens during the PR interval
time to start of atrial depolarization to start of ventricular depolarization
what happens during th QRS complex
ventricular depolarization also includes atrial repolarizationwh
what happens during the T wave
ventricular repolarization
what happens during the QT interval
time between start of ventricular depolarization and end of repolarization
QT is ______ and must be adjusted at a HR of ______ bpm
rate dependent; greater than 60 bpm
what is prolonged QT in men and women
- women: greater than 460msec
- men: greater than 450 msec
what are the sites of arrhythmias
- atrial
- junctional
- ventricular
what are examples of tachycardia
- a fib
- SVT
- ventricular tachycardia
- ventricular fibrillation
what are examples of bradycardia
heart block and asystole
what are the mechanissm of cardiac arryhthmias
- delayed after depolarization
- re-entry
- ectopic pacemaker activity
- heart block
what are class I antiarrhythmic medications
- Na+ channel blockers
- subgroups: Ia, Ib, and Ic
what are class II antiarrhythmic medications
beta adrenoreceptor blockers
what are class III antiarrhythmic medications
K+ channel blockers
what are class IV antiarrhythmic medications
Ca2+ channel blockers