What bring the blood back to heart?

The heart is a vital organ that pumps oxygen-rich blood throughout the body via a network of blood vessels. The process of returning deoxygenated blood back to the heart is called venous return. Several mechanisms contribute to venous return, including:

1. Skeletal Muscle Pump: When skeletal muscles contract, such as during walking or arm movements, they compress nearby veins. The pressure exerted by the contracting muscles helps propel the blood within the veins toward the heart.

2. Respiratory Pump: During inhalation, the diaphragm and other respiratory muscles contract, creating a decrease in intrathoracic (inside the chest) pressure. This negative pressure draws blood from the large veins in the abdomen into the chest, promoting venous return.

3. Heart's Suction Effect: As the heart relaxes during diastole (the filling phase), it creates a vacuum that draws blood from the veins into its chambers. The one-way valves in the veins (venous valves) ensure that the blood flows only towards the heart and prevents backflow.

4. Vis A Tergo ("Force From Behind"): This refers to the continuous generation of blood pressure within the arteries and capillaries. The pressure generated by the heart's contractions pushes the blood forward through the arteries and forces the deoxygenated blood back towards the heart via veins.

5. Venous Valves: Veins contain one-way valves that prevent backflow and maintain forward flow of blood towards the heart. These valves ensure that blood does not pool or flow in the wrong direction, promoting efficient venous return.

These factors work in conjunction to ensure a steady and adequate flow of deoxygenated blood from various parts of the body back to the heart for re-oxygenation and subsequent pumping to the lungs and systemic circulation.