<prompt> Preload is increased by -Increased blood volumeIncreased total peripheral resistanceStandingSitting  <response>: Ans. is a i.e.. Increase blood volume Preload Degree of ventricular filling during diastoleo Cardiac preload is represented by volume of venous blood that distends the ventricle, i.e., venous return determines the preload. An increase in preload, i.e., increase in venous return results in a higher end-diastolic volumeQ PreloadQ.o This results in stretching of myocardial fiber and this increase in length of myofibril increases the strength of cardiac contraction in accordance with the Frank-Starling law or Starlings law of the hearto According to Starlings lawr, greater the initial length of muscle fiber, greater is the force of contraction,o The initial length of muscle fiber length of fiber at the initiation of contractionsystole refers to length of the fiber at the end of the diastole, i.e., end-diastolic fiber length.o Thus, the factors which improve venous return increase the cardiac output by increasing end-diastolic ventricular volume and length, i.e.. preload,o Opposite is true for factors which decrease venous return. Stroke volume Stroke volumeFactors Increasing end-diastolic ventricular muscle fiber length Factors increasing venous return or preloadFactors decreasing end-diastolic ventricular muscle fiber length Factors decreasing venous return or preloado Increased total blood volumeQo Decreased total blood volumeo Increased venous toneQo Decreased venous toneo Increased pumping action of skeletal muscleo Decreased pumping action of skeletal muscleso Increased negative intrathoracic pressureQ e.g. inspirationo Less negative or positive intrathoracic pressure expirationo Sitting or standingQ venous pooling of bloodo Lying down from sitting or standing position o Sympathatic discharge causing decrease in venous capacitance by decreasing venous compliance 