The human body has a double circulatory system, meaning blood passes through the heart twice during each complete circuit. This system is divided into two main types of blood circulation: systemic circulation and pulmonary circulation. Additionally, there is a third type called coronary circulation that specifically serves the heart.

1. Systemic Circulation

Systemic circulation is responsible for delivering oxygen-rich blood from the heart to the rest of the body and returning oxygen-poor blood back to the heart.

• Pathway:

  • Oxygenated blood is pumped from the left ventricle of the heart into the aorta.
  • The aorta branches into arteries, which further divide into arterioles and capillaries.
  • In the capillaries, oxygen and nutrients are delivered to body tissues, and carbon dioxide and waste products are absorbed.
  • The deoxygenated blood is collected by venules, which merge into veins and eventually drain into the superior and inferior vena cava.
  • The vena cava returns the deoxygenated blood to the right atrium of the heart.

• Function:
  To supply oxygen and nutrients to the body's tissues and organs while removing waste products like carbon dioxide.

2. Pulmonary Circulation

Pulmonary circulation carries deoxygenated blood from the heart to the lungs for oxygenation and then brings oxygenated blood back to the heart.

• Pathway:

  • Deoxygenated blood is pumped from the right ventricle of the heart into the pulmonary arteries.
  • The pulmonary arteries carry the blood to the lungs, where it picks up oxygen and releases carbon dioxide.
  • The oxygen-rich blood is then carried back to the left atrium of the heart via the pulmonary veins.

• Function:
  To exchange gases (oxygen and carbon dioxide) between the blood and the lungs, making the blood oxygen-rich.

3. Coronary Circulation

Coronary circulation supplies the heart muscle (myocardium) with oxygen and nutrients. It ensures the heart itself receives the energy required for continuous pumping.

• Pathway:

  • Oxygenated blood is delivered to the heart muscle through the coronary arteries, which branch off from the aorta.
  • After supplying oxygen and nutrients, the deoxygenated blood is collected by coronary veins, which empty into the right atrium via the coronary sinus.

• Function:
  To nourish the heart muscle and remove waste products to maintain its function.

Summary of Functions: