Question 18N.3.SL.TZ0.17
| Date | November 2018 | Marks available | [Maximum mark: 5] | Reference code | 18N.3.SL.TZ0.17 |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | Explain, Outline, State | Question number | 17 | Adapted from | N/A |
An electrocardiogram (ECG) records the electrical activity of the heart over a period of time using electrodes placed on the skin. The ECG shown is from a patient whose heart was beating irregularly until it was treated using a defibrillator (arrows) which restored normal electrical activity.
State how many normal heartbeats are shown in the ECGs.
[1]
8 ✔
Outline how a defibrillator is used to restore normal heartbeat.
[2]
a. «paddles/electrodes/defibrillator» deliver an electric shock to the heart ✔
b. depolarizes cardiac muscle ✔
c. enables the pacemaker/SA node to regain control ✔
Explain what is occurring in the heart during the peak of electrical activity as indicated by the R wave on the ECG.
[2]
a. impulses initiated from the AV node spread across heart ✔
b. impulses travel along Purkinje fibres/across ventricles ✔
c. causing depolarization of the ventricles
OR
that triggers ventricular contraction ✔