Knowra Venous return Venous return Venous return is the flow of blood through veins toward the heart. It depends on pressure gradients and mechanisms that help move blood against gravity, especially from the limbs.
Mean systemic filling pressure : The pressure in the systemic circulation when blood flow is absent, reflecting vascular filling and tone. It helps set the pressure gradient that drives blood from systemic veins toward the right atrium.
Cardiac output : The volume of blood pumped by one ventricle per unit time. In steady circulation, venous return and cardiac output must match over time.
Orthostatic hypotension : A sustained fall in blood pressure after standing, often causing dizziness or faintness. Standing can pool blood in the legs and temporarily reduce venous return and cardiac output.
Venous capacitance : The capacity of veins to contain blood at a given pressure. Capacitance describes storage, whereas venous return describes blood flow toward the heart.
Venous valves : One-way folds in veins that limit backward blood flow. They prevent gravity from reversing the upward flow of blood in many limb veins.
Systemic circulation : The blood vessels carrying blood between the left heart and the body's tissues, excluding the pulmonary circulation. Venous return is the returning limb of this circuit, bringing systemic blood back to the right heart.
Exercise physiology : The study of how the body responds to physical activity. During exercise, muscle contractions and breathing changes increase blood return while circulation accelerates.
Preload : The stretch of ventricular muscle at the end of filling, before contraction. Venous return can influence ventricular filling and preload, but the two are not interchangeable.
Skeletal muscle pump : The compression of veins by contracting skeletal muscles, which propels blood toward the heart. Walking and other muscle contractions squeeze limb veins and assist venous return.
Pressure gradient : A difference in pressure between locations that can drive fluid flow. Venous blood flows toward the heart because pressure is generally higher upstream than at the right atrium.
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