Venous return

Venous Return

Venous return (pronounced: /ˈviː.nəs rɪˈtɜːn/) is the rate of blood flow back to the heart. It is an important factor in determining the output of the heart during cardiac cycle.

Etymology

The term "venous return" is derived from the Latin words "vena" meaning "vein" and "returnare" meaning "to return". It refers to the process of blood returning to the heart via the veins.

Definition

Venous return is the flow of blood from the peripheral veins back to the right atrium of the heart. The rate of venous return is influenced by several factors including the pressure gradient between the peripheral veins and the right atrium, the compliance of the veins, and the resistance to blood flow in the veins.

Factors Affecting Venous Return

Several factors can affect the rate of venous return:

Blood Volume: An increase in blood volume increases venous return by distending the veins and increasing the pressure gradient from the peripheral veins to the right atrium.
Venous Compliance: Decreased venous compliance (i.e., stiffer veins) can increase venous return by increasing the pressure in the veins.
Muscle Pump: The contraction and relaxation of skeletal muscles, particularly in the legs, can help propel blood towards the heart, thereby increasing venous return.
Respiratory Pump: Changes in intrathoracic pressure during respiration can also affect venous return. During inspiration, the decrease in intrathoracic pressure can facilitate venous return to the heart.

Related Terms

Cardiac Output: The volume of blood the heart pumps per minute. It is directly related to the venous return.
Frank-Starling Mechanism: The inherent ability of the heart to adapt to changing volumes of inflowing blood. The greater the volume of blood entering the heart during diastole (i.e., the greater the venous return), the greater the volume of blood ejected during systolic contraction (i.e., the greater the stroke volume).