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ECG
Anatomy & Physiology
Term | Definition |
---|---|
Automaticity | Ability of pacemaker cells to INITIATE an electric stimulus spontaneously WITHOUT external stimulus |
Excitability is the ability of cardiac muscle cells to ___ to an ___ electric stimulus | Respond; outside |
Conductivity is the ability of cardiac cells to ___ an electric impulse and propagate the impulse to __ | Receive; next cell |
Contractility is the ability of cardiac cells to shorten ___ | In respond to electric stimulus |
In diastole the __ of the cell is electrically more ___ than __ of the cell | Inside; negative; outside |
In resting state, there are more __ ions than __ inside the cell | K+, Na+ |
Depolarization is the ___ of the cell membrane | Electrical excitation |
Repolarization is the ___ of cell membrane to its ___ ___ | Return; resting states |
In repolarization, the channels for __ open and it flows out, taking the __ charge with it | K+, positive |
At end of ___, the Na-K pumps in cell membrane move potassium in and sodium out of cells | Repolarization |
___ is the primary pacemaker of the heart | SA node |
SA Node cells depolarize automatically at rate of ___ | 60-100 |
AV Node can function as the ___ of the heart | Backup pacemaker |
AV Node automatically depolarize at rate of ___ | 40-60 |
AV Node ___ the conduction of the impulse from atria to ventricles from dangerously fast rate | Slows |
Bundle of HIS is | Short bundle of fibers at bottom of AV node leading to BBs |
Bundle Branches | Carry impulse into R and L ventricles. |
Purkinje fibers act as the ___ pacemaker, automatically depolarizing at rate of | Final backup; 20-40 |
P wave represnts | Atrial depolarization as impulse travels through atria |
PR interval represents | Atrial depolarization + AV conduction time |
Normal PR interval is | 0.12-0.20 |
QRS represents | Ventricular depolarization and intraventricular conduction time |
Q wave represents | 1st negative deflection from baseline |
R wave represents | 1st POSITIVE deflection from baseline (ALWAYS upright) |
S wave represents | Negative deflection following R |
Normal width of QRS | 0.06-0.10 |
T wave repesents | Ventricular repolarization |