Our hearts beat continuously to power our circulatory system, and if we listen closely, we can actually see and hear the electrical impulses that drive each contraction. In this experiment, you will learn how to record an electrocardiogram, or EKG, using the Human SpikerBox to observe the waveforms behind each beat and explore how your heart communicates with your brain in real time.
This experiment helps you explore the basics of electrocardiography and discover how your brain regulates heart rate through its control center in the medulla oblongata. You will learn how the specialized cells in the heart coordinate each beat with extended action potentials and how changes in activity or emotion can alter your heart’s rhythm.
The heart relies on specialized pacemaker cells to produce rhythmic electrical impulses, causing coordinated muscle contractions that pump blood throughout your body. These impulses are not as short as skeletal muscle spikes but are longer and have distinct waveforms labeled P, Q, R, S, and T. You can visualize them by placing electrodes on your skin and recording with the Human SpikerBox. The resulting waveform can be influenced by signals from your brain, which can adjust the heart rate in response to exercise, emotional states, or stress hormones such as adrenaline.
You will place adhesive electrodes on the inner side of your wrists and on the back of one hand (Configuration 1 below), then connect them to the SpikerBox. Relax and hold your arms still so muscle activity does not interfere with the recording. Connect the SpikerBox to the SpikeRecorder software. Open the config menu (gear icon in the top left) and select the ECG filter setting. Observe the rhythm that appears on the screen and note how these waveforms correspond to the electrical signals coordinating your heartbeats.
If you find too much noise in your signal, try using a battery-powered laptop or improve electrode placement by moving them closer to your chest. After you have a stable waveform, try increasing your heart rate by a brief exercise like jumping jacks before reconnecting, and watch the heart rate change as your body recovers from exertion. Pay attention to how your heart adapts automatically, guided by the nervous system’s instructions to speed up or slow down as needed.
Consider whether you are recording the spontaneous cardiac action potentials initiated by pacemaker cells or the muscle potentials that follow them. Think about how your waveforms might change when you adjust the electrode positions or your posture. Reflect on how factors like caffeine, adrenaline, or recent exercise might affect what you see on screen. Imagine measuring heart rates under various conditions such as standing outside on a cold day or after sipping a warm drink, and see if you observe measurable differences in how your heart responds.
