Stroke volume is primarily regulated by three factors: preload, afterload, and contractility. Preload refers to the degree of stretch of the cardiac muscle fibers before contraction, influenced by venous return. Afterload is the resistance the heart must overcome to eject blood, primarily determined by arterial pressure and vascular resistance. Contractility refers to the intrinsic strength of the heart muscle's contraction, which can be affected by factors such as sympathetic stimulation and the availability of calcium.
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