Question

Briefly mention the steps in double-circulation through human heart.

Hint:

Double circulation = Pulmonary + Systemic circulation. Blood passes through heart twice in one cycle.

Answer 1

Double Circulation in Human Heart:

Double circulation means that blood passes through the heart twice during one complete cycle of circulation. It involves two separate pathways: 1. Pulmonary circulation 2. Systemic circulation

Steps in Double Circulation:

Step 1: Entry of Deoxygenated Blood
– Deoxygenated blood from different parts of the body enters the right atrium through the superior and inferior vena cava.

Step 2: Right Atrium to Right Ventricle
– The right atrium contracts and pushes blood into the right ventricle through the tricuspid valve.

Step 3: Pulmonary Circulation (Heart to Lungs)
– The right ventricle contracts and pumps deoxygenated blood to the lungs through the pulmonary artery. – In the lungs, carbon dioxide is released and oxygen is absorbed.

Step 4: Return of Oxygenated Blood
– Oxygenated blood from the lungs returns to the left atrium through the pulmonary veins.

Step 5: Left Atrium to Left Ventricle
– The left atrium contracts and pushes blood into the left ventricle through the bicuspid (mitral) valve.

Step 6: Systemic Circulation (Heart to Body)
– The left ventricle contracts and pumps oxygenated blood to all parts of the body through the aorta. – Oxygen is supplied to body tissues and carbon dioxide is collected.

Conclusion:
In double circulation, blood passes through the heart twice—once during pulmonary circulation (heart → lungs → heart) and once during systemic circulation (heart → body → heart). This ensures efficient oxygen supply to the body.