Term
| When does the P wave begin? |
|
Definition
| When signal from SA node spreads through atria and depolarises them |
|
|
Term
|
Definition
| The time is takes for the impulse to travel from the SA node to the AV node |
|
|
Term
| Describe the appearance of the QRS complex |
|
Definition
Q - small downward deflection
R - tall sharp peak
S - final downward deflection |
|
|
Term
| When does the QRS complex occur? |
|
Definition
| When signal from AV node spreads through ventricular myocardium and depolarises muscle |
|
|
Term
| Why does the QRS complex have the shape it does? |
|
Definition
| Due to different sizes of two ventricles - i.e. different times to depolarise them |
|
|
Term
| When does ventricular systole begin? |
|
Definition
|
|
Term
| Why do atrial repolarisation and diastole, which also occur during QRS, not show on an ECG? |
|
Definition
| Weak signal obscured by more muscular ventricles |
|
|
Term
| When does the ST segment occur? |
|
Definition
| Plateau in myocardial action potential - time ventricles contract and eject blood |
|
|
Term
| What generates the T wave? |
|
Definition
| Ventricular repolarisation immediately before diastole |
|
|
Term
| To ventricles take longer to depolarise or repolarise? |
|
Definition
|
|
Term
| What effect does that fact that ventricles take longer to repolarise than depolarise have on the shape of the T wave compared to the QRS complex? |
|
Definition
| T wave smaller and more spread than QRS and has rounder peak |
|
|
Term
| What part of an ECG shows ventricular repolarisation? |
|
Definition
|
|
Term
| What part of an ECG shows when the signal from the AV node spreads through ventricular myocardium and depolarises them? |
|
Definition
|
|
Term
| What part of an ECG shows the times it takes for the impulse to travel from the SA node to the AV node? |
|
Definition
|
|
Term
| What part of an ECG shows when the signal from the SA node spreads through the atria and depolarises them? |
|
Definition
|
|
