Flow of Blood Through the Heart

FLOW OF BLOOD THROUGH THE HEART

Right Side of Heart

The heart functions as a powerful muscular pump that maintains continuous circulation of blood throughout the body. Blood flow through the heart follows a fixed and well-organized pathway to ensure proper oxygenation and nutrient supply.

The two largest veins of the body, the superior vena cava and inferior vena cava, bring deoxygenated blood from different parts of the body and empty it into the right atrium of the heart.

From the right atrium, blood passes through the right atrioventricular valve (tricuspid valve) into the right ventricle. This valve allows blood to move forward and prevents backward flow into the atrium during ventricular contraction.

When the right ventricle contracts, blood is pumped into the pulmonary artery (pulmonary trunk). This artery is unique because it is the only artery in the body that carries deoxygenated blood.

The opening of the pulmonary artery is guarded by the pulmonary valve, which is made up of three semilunar cusps. This valve prevents the blood from flowing back into the right ventricle when the ventricle relaxes.

The pulmonary artery divides into left and right pulmonary arteries, which carry venous (deoxygenated) blood to the lungs. In the lungs, gaseous exchange takes place, where:

• Carbon dioxide is removed from the blood
• Oxygen is absorbed into the blood

This process is essential for maintaining normal respiration and cellular function.

After oxygenation in the lungs, blood is returned to the heart by two pulmonary veins from each lung. These veins carry oxygenated blood back to the left atrium.

Summary of Blood Flow (Right Side of Heart):

Left Side of Heart

Blood collected in the left atrium then passes through the left atrioventricular valve (bicuspid or mitral valve) into the left ventricle. This valve ensures that blood flows only in one direction and prevents regurgitation into the atrium.

The left ventricle has thicker muscular walls compared to the right ventricle because it has to pump blood to the entire body. When the left ventricle contracts, blood is pumped into the aorta, the largest artery of the body, which supplies oxygenated blood to all organs and tissues.

The opening of the aorta is guarded by the aortic valve, which is also composed of three semilunar cusps. This valve prevents the backflow of blood into the left ventricle when it relaxes.

From this sequence of events, it is clear that blood flows from the right side of the heart to the lungs, and then to the left side of the heart, a process known as pulmonary circulation. Blood pumped from the left ventricle to the body is called systemic circulation.

It is important to note that both atria contract at the same time, followed by the simultaneous contraction of both ventricles. This coordinated activity ensures efficient pumping and continuous blood flow.

Summary of Blood Flow (Left Side of Heart):