Question 41

The ECG systematically measures the stages at which the "wave of excitation" occurs within the heart and records them.

The ECG captures the distinct phases of the "wave of excitation" as it propagates through the heart, specifically detailing the sequence from the SA node to the AV node, which is critical for understanding cardiac function.

A) Electric currents within the body are due to electrostatic charges set off by the heart. Medical staff are trained to recognize any abnormalities within the heart.

This option incorrectly attributes the source of electric currents to electrostatic charges rather than the heart's electrical activity. While it mentions the role of medical staff in recognizing abnormalities, it does not summarize the process of the ECG or the phases of excitation adequately.

B) Every individual has unique electric currents on the surface of the body. The ECG measures and records these electric currents.

This statement is misleading as it suggests that the ECG measures unique electric currents for each person, rather than focusing on the specific electrical activity of the heart. It does not address the systematic measurement of the "wave of excitation" or the distinct phases described in the extract.

C) The ECG systematically and rather quickly measures the stages at which the "wave of excitation" occurs within the heart and records them. This wave has three distinct steps that spread from the SA node to the AV node.

This option accurately reflects the passage's content, emphasizing the systematic measurement of the "wave of excitation" and its three distinct phases, which is the core focus of the extract. It effectively summarizes the ECG's function in relation to heart activity.

D) The ECG measures the electric currents within the body. These currents are detected on the surface of the body when the body is connected to an amplifier.

While this option describes the function of the ECG, it lacks the specificity regarding the "wave of excitation" and the sequential phases of cardiac activity. It does not capture the comprehensive nature of the ECG's role in measuring the heart's electrical activity as described in the passage.

Conclusion

Option C is the most accurate summary of the passage, as it encompasses the systematic measurement of the "wave of excitation" through the heart and details the phases involved. The other options fail to adequately represent the complexities of the ECG's function or misinterpret the source and nature of the electric currents involved. Thus, C is the definitive choice that aligns with the passage's content.