Electrocardiograms

The marks available for each question are shown in square brackets at the end of the question

1. The diagram below shows the heart.

(a) Which chamber of the heart is labelled with the letter B? [1]

(b) Which letter represents the SA node? [1]

(c) What does the SA node do? [1]

2. Below is an electrocardiogram (ECG) of a patient.

(a) Time is plotted on the horizontal axis. Which quantity is plotted on the vertical axis? [1]

(b) Use the ECG to work out the average time period of the heartbeat. Show your working. [2]

(c) Work out the heart-rate in beats per minutes [2]

(d) A doctor viewing the ECG is concerned that the person may have a heart problem. Explain why the doctor is concerned [2]

B

C

D

A

0

0.4

0.8

1.2

2.0

time(s)

1.6

Medical Physics

Worksheet

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