6. Circulation of blood in heart

1. The right atrium receives deoxygenated blood from different parts of the body through the main veins - superior vena cava, inferior vena cava and coronary sinus. The right atrium relaxes during the process to collect the deoxygenated blood.

 

2. The right atrium pumps the blood to the right ventricle. Thus, the deoxygenated blood from the right atrium is sent to the right ventricle.

 

3. The right ventricle contracts, and the blood enters the pulmonary artery. The pulmonary trunk emerges from the right ventricle and divides into right and left pulmonary arteries. The right and left pulmonary arteries supply deoxygenated blood to the right and left lungs, respectively.

 

Through the pulmonary artery, blood is pumped to the lungs for oxygenation. At the lungs, the exchange of gases takes place.

 

4. Pulmonary veins bring oxygenated blood from the lungs to the left atrium. The left atrium relaxes during the process to collect the oxygenated blood.

 

5. From the left atrium, the blood reaches the left ventricle due to the contraction of the left atrium. The oxygenated blood is forced into the ventricle through the atrioventricular openings by the atrial contraction.

 

6. Next, the left ventricle contracts and blood is pumped out to the various parts of the body through the aorta. The aorta supplies the oxygenated blood to various parts of the body. The coronary arteries supply blood to the heart.

The blood circulates in the body as oxygenated and deoxygenated blood. There are three types of circulation:

 

1. Systemic circulation:

Systemic circulation carries oxygen to the tissues of the body and also removes \(CO_2\) from the tissues. Aorta carries oxygenated blood to all the organs of the body.

 

2. Pulmonary circulation:

Pulmonary circulation starts in the right ventricle. The pulmonary artery emerges from the right ventricle and reaches the lungs with deoxygenated blood. Pulmonary veins collect oxygenated blood from the lungs and supply it to the left atrium of the heart.

 

 

3. Coronary circulation:

The coronary arteries that branch off from the aortic arch supply oxygenated blood to the cardiac muscles. Deoxygenated blood from the cardiac muscles is drained into the right atrium by the coronary sinuses.

 

  

Double circulation:

In double circulation, oxygenated blood does not mix with deoxygenated blood.

The separation of the heart is important to avoid the mixing of oxygenated and deoxygenated blood. The separation also allows for an efficient supply of oxygen to the body.

 

All the vertebrates have a chambered and muscular heart. However, in some animals, the deoxygenated and oxygenated blood is mixed and goes through the heart only once. This type of circulation is called single circulation.