IMED3001 Study Guide - Quiz Guide: Cardiac Output, Afterload, Blood Pressure
28 Dec 2020
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Imed3001: preload (lab for ecg tracing and cardiac function) We will focus on filling of the heart during diastole. Blood flows into the ventricle when the heart is relaxed, so the volume increases along the diastolic (passive) pressure-volume curve. The more blood flows into the heart, the higher the pressure even before contraction. Diastole ends when the heart begins to contract, and the edv and edp (end-diastolic pressure) are defined by this point. Preload variations are probably the most important determinants of cardiac output under normal circumstances. As discussed above, edv is the best descriptor of preload, but is difficult to quantitate precisely in-vivo. Edp is a surrogate measure, and is nonlinearly related to edv (according to the diastolic (passive) pressure-volume relationship). The strength of atrial active contraction can modulate ventricular preload. The terminal contraction of the atrium serves primarily to augment ventricular preload prior to ejection.
