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The HEART Keeps Pumping and Pumping and Pumping. . . |
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The Heart - In Depth Function Now, for a more in depth look at the heart. To analyze the function of the heart a researcher can look at electrocardiograms (ECG) or measure heart pressures. Every part of the heart is not pumping at the same time. There are periods of systole (contraction) and diastole (relaxation) to efficiently pump blood. The phases of systole and diastole are regulated by waves of current and can be visualized by an ECG similar to the one below.
(http://students.med.nyu.edu/erclub/ekgguide.pdf) The P wave corresponds to the depolarization and contraction of the atria to cause the blood to flow to the ventricles. The QRS complex corresponds to the depolarization of the ventricles to cause the blood to flow out of the ventricles and either to the lungs or the rest of the body. The T wave corresponds to the repolarization of the ventricles. The speed of the heart beat can be monitored by the distance between the QRS peaks. When the distance between these peaks varies on consecutive beats, the heart beat is considered to be irregular. Irregular heart beats can cause serious complications and even death.
(http://sprojects.mmi.mcgill.ca/cardiophysio/EKGwiggers.htm) Wigger Diagram The best way to analyze this diagram is to read from left to right but also vertically. Try to follow the pathway of the individual events then the cycle makes more sense. For example, increases in pressure correlate to the flow of blood. Also notice that this entire process takes less than 0.7 sec. It is important to know this information to properly analyze the presentation of a patient. The following activities should assist in the understanding of this cycle. |
