OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

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What is one role of the heart's natural pacemaker?

To repair damaged tissues
To regulate heartbeats
To control blood pressure
To increase heart size

The correct answer is: To regulate heartbeats

The heart's natural pacemaker, known as the sinoatrial (SA) node, plays a crucial role in regulating heartbeats. This specialized group of cells is located in the right atrium of the heart and generates electrical impulses that trigger the contraction of the heart muscle. The SA node sends out signals at regular intervals, prompting the heart to beat in a coordinated manner. This ensures that the heart pumps blood efficiently throughout the body. The pacemaker essentially determines the heart rate by controlling the timing of when the heart's chambers contract. If the pacing is disrupted, it can lead to irregular heart rhythms, which can impact overall heart function and health. The correct answer highlights this fundamental function of the SA node in maintaining the rhythmic beating of the heart, which is essential for effective circulation.