Definition
- Venous return is the volume of blood returning to the right atrium from the systemic venous circulation per unit time.
Factors Affecting Venous Return
Factors affecting venous return
Factor
Skeletal muscle pump
- Effect on venous return
- Muscle contraction compresses veins; valves direct flow towards heart → increases
Thoracic pump
- Effect on venous return
- Inspiration → more negative intrathoracic pressure → falling central venous pressure → increases
Abdominal pump
- Effect on venous return
- Inspiration → rising intra-abdominal pressure compresses vessels, blood pushed towards heart → increases
ECF volume
- Effect on venous return
- Increased ECF/plasma volume → increases; decreased ECF volume → decreases
Sympathetic activity
- Effect on venous return
- Increased tone → venoconstriction → increases; decreased tone → venodilation → decreases
Right atrial pressure
- Effect on venous return
- Increased right atrial pressure → decreases (inverse relation)
Degree of filling of systemic circulation
- Effect on venous return
- Increased mean circulatory filling pressure → increases
Resistance to venous return
- Effect on venous return
- Increased venous resistance → decreases