Difference Between Pulmonary Circulation vs. Systemic Circulation

Main Difference

The main difference between the Pulmonary Circulation and Systemic Circulation is that Pulmonary Circulation is the transport of de-oxygenated blood from the heart to lungs and back to the heart and Systemic Circulation is the transportation of the oxygenated blood from the heart to the body and back to the heart.

Pulmonary Circulation vs. Systemic Circulation

Pulmonary circulation is the transport of deoxygenated blood from the heart to lungs and after oxygenation in lungs back to heart while Systemic circulation is the transportation of the oxygenated blood from the heart to the body and bringing back deoxygenated blood of the body to the heart. In Pulmonary circulation deoxygenated blood from the right ventricle is pumped to lungs through pulmonary arteries whereas, in Systemic circulation, the oxygenated blood from lungs enters into the left ventricle through pulmonary veins. Pulmonary circulation is a lower pressure system, while Systemic circulation is a higher pressure system. Pulmonary circulation involves pulmonary valves. On the other hand, Systemic circulation involves aortic valves. Pulmonary circulation, when ends then systemic circuit begins while when the Systemic circulation ends the Pulmonary circulation begins.

Comparison Chart

Pulmonary CirculationSystemic Circulation
The Pulmonary circulation is the transport of deoxygenated blood from the heart to lungs and after oxygenation in the lungs back to the heart.The Systemic circulation is the transportation of the oxygenated blood from the heart to the body and bringing back deoxygenated blood of the body to the heart.
Route of Circulation
From the right ventricle to the lungs.From lungs to the left ventricle.
Blood Vessels Involved
Pulmonary arteriesPulmonary veins
Valves Involved
Pulmonary valvesAortic valves

Pressure Difference

Pulmonary circulation is a low-pressure system.Systemic circulation is a high-pressure system.
Major Role
Oxygenation of bloodSupply oxygen and nutrients to body and collection of waste products and gases.

What is Pulmonary circulation?

The pulmonary circulation is the transportation of de-oxygenated blood from the heart to the lungs for the re-saturation of the blood with oxygen before entering of blood into the systemic circulation. The pulmonary circulation system is the only pathway through which the complete cardiac output passes. The main role of the pulmonary circulation is that it allows respiratory gas exchange. Pulmonary circulation is a low-pressure and high-flow system to play the role of respiratory gas exchange. Right atrium of the heart receives the deoxygenated blood from the lower half of the body through inferior vena cava, and deoxygenated blood from the upper half of the body is received through superior vena cava. The right ventricle receives blood from the right atrium through the tricuspid valve. Blood from Right ventricle flows into the pulmonary artery through the pulmonic valve before its delivery to the lungs. Within the lungs, blood moves to the numerous pulmonary capillaries releases carbon dioxide and is restocked with oxygen. When blood is fully saturated with oxygen, it is transported through the pulmonary vein into the left atrium. The right atrium pumps blood via the mitral valve and into the left ventricle. So the pulmonary circulation conducts the whole cardiac output from the pulmonary artery with significant low driving pressure having mean of Ppa 15 to 20 mm Hg to right atrium having Plan from 7-12mm Hg. In pulmonary circulation blood flow is regulated through an active mechanism which helps in adjusting blood flow to the relatively smaller lung area. Pulmonary circulation is affected by a number of the factor under physiological and pathological states, which include lung inflation, gravity, alveolar surface tension, and blood viscosity.

What is Systemic circulation?

The Systemic circulation is the circulation of blood, which transports oxygenated blood from the heart to the body and returns the deoxygenated blood from the body to heart. Blood from the left ventricles is pumped through aorta and arterial branches to the arterioles. Blood is then taken by capillaries and capillaries drain into the veins through venules. Blood returns through venae cavae to the right atrium of the heart. The carotid arteries are branched off from the aorta. Some arteries branch off from the aortic arch e.g. brachiocephalic, left common carotid, and left subclavian arteries. Internal carotid and vertebral arteries transport blood supply to the brain. The subclavian arteries supply blood to the upper extremity. Some arteries branch off from the abdominal aorta and supply blood to the abdominal viscera. Lumbar arteries supply blood to the spinal cord and muscles. External iliac artery branch off and supply blood to the lower extremity. Internal iliac artery supply blood to the pelvic viscera. The pressure of the arterial system is responsible for maintaining systemic blood flow. The Systemic pathway is comprised of many circuits, and each circuit has its own arteriolar resistance. Each circuit determines blood flow, which is independent of the overall flow and pressure e.g. the blood flow in the muscles is increased during exercise.

Key Differences

  1. Pulmonary circulation is the transport of deoxygenated blood from the heart to lungs and after oxygenation in lungs back to heart while Systemic circulation is the transportation of the oxygenated blood from the heart to the body and bringing back deoxygenated blood of the body to the heart.
  2. The Pulmonary circulation involves transportation of deoxygenated blood from right ventricle to heart while the Systemic circulation involves transportation of oxygenated blood from the lungs to the left ventricle.
  3. Pulmonary circulation involves pulmonary arteries, and the Systemic circulation involves pulmonary veins.
  4. The Pulmonary circulation plays the major role of oxygenation of the blood, and the Systemic circulation plays the major role of supply of oxygen and nutrients to body tissues.

Conclusion

The main conclusion of the above discussion is that Pulmonary and Systemic circulation is a completely different set of circulation that together make up the circulatory system of the body.

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