How does the heart pump blood class 10?

The heart pumps blood through a rhythmic cycle of contraction (systole) and relaxation (diastole), ensuring efficient circulation throughout the body.

Here's a breakdown of the process:

The Cardiac Cycle:

The heart's pumping action can be understood as a cyclical process consisting of two main phases: diastole (relaxation and filling) and systole (contraction and ejection).

1. Diastole (Relaxation and Filling):

   • The heart muscles relax, and the atria (upper chambers) fill with blood.
   • Blood from the body enters the right atrium via the superior and inferior vena cava.
   • Blood from the lungs enters the left atrium via the pulmonary veins.
   • As the atria fill, pressure increases, causing the tricuspid valve (between the right atrium and right ventricle) and the mitral valve (between the left atrium and left ventricle) to open.
   • Blood flows passively from the atria into the ventricles (lower chambers).

2. Systole (Contraction and Ejection):

   • The atria contract, pushing any remaining blood into the ventricles.
   • The ventricles then contract powerfully.
   • The increased pressure within the ventricles forces the tricuspid and mitral valves to close, preventing backflow into the atria.
   • The pressure continues to rise, eventually exceeding the pressure in the pulmonary artery (leading to the lungs from the right ventricle) and the aorta (leading to the rest of the body from the left ventricle).
   • The pulmonary valve (between the right ventricle and pulmonary artery) and the aortic valve (between the left ventricle and aorta) open.
   • Blood is ejected from the ventricles: the right ventricle pumps deoxygenated blood to the lungs via the pulmonary artery, and the left ventricle pumps oxygenated blood to the rest of the body via the aorta.
   • Once the ventricles have emptied and the pressure decreases, the pulmonary and aortic valves close to prevent backflow into the ventricles. The cycle then begins again.

Summary of Blood Flow:

1. Deoxygenated blood enters the right atrium.
2. Blood flows from the right atrium to the right ventricle.
3. The right ventricle pumps blood to the lungs (via the pulmonary artery) to pick up oxygen.
4. Oxygenated blood returns from the lungs to the left atrium (via the pulmonary veins).
5. Blood flows from the left atrium to the left ventricle.
6. The left ventricle pumps blood to the rest of the body (via the aorta).

Valves Ensure Unidirectional Flow:

The heart valves (tricuspid, mitral/bicuspid, pulmonary, and aortic) are crucial in maintaining the unidirectional flow of blood. They open and close in response to pressure changes within the heart chambers, ensuring blood moves forward and preventing backflow.