NURS 3014 Lecture Notes - Lecture 4: Nuclear Medicine, Radionuclide Angiography, Fluid Balance
23 May 2017
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Pns: when the sns is activated, both heart rate and stroke volume increase, when the ans is activated, heart rate decreases, while measurement of heart rate is easy, stroke volume is more difficult to measure. The amount of blood within the ventricle just before systole. Preload increases ventricular pressure and stretches the ventricular wall. Like a rubber band, there needs to be a certain amount of stretching to produce optimal ejection. Too much or too little stretch, however, decreases the amount of blood ejected. The major factor affecting preload is venous return the volume of blood that enters the ventricle during diastole. Another factor is ventricular compliance, or the elasticity when blood enters the ventricular. Elasticity is decreased when muscle thickens (hypertrophy) or there is fibrotic tissue (replaced dead myocardial tissue, as in mi and stiffens the muscle): afterload. Refers to the amount of resistance to the ejection of blood from the ventricle.
