Question

a) Explain in brief the mechanism of circulation of blood in the human body.
(b) "Lymph is another type of fluid involved in transportation" Justify this statement by explaining the process.



CBSE Class X Science LA (5 Marks)

Answer 1

(a) Oxygen-rich blood from the lungs comes to the thin-walled upper chamber of the left atrium, through the pulmonary vein. When the muscular left ventricle contracts, the blood is pumped throughout the body. When the right atrium expands, the deoxygenated blood in the body comes to the upper chamber of the right atrium. As the right atrium contracts, the corresponding lower chamber i.e., right ventricle dilates on the left i.e., on the left atrium. This left atrium relaxes while receiving this blood. After this, this left atrium contracts and the next chamber i.e., left ventricle expands so that the blood is transferred to the lungs for oxygenation. Ventricles pump the blood into various organs. Hence, they have thicker musuclar walls than the atria.

Answer 2

Answer:

(a) Oxygen-rich blood from the lungs comes to the thin-walled upper chamber of the left atrium, through the pulmonary vein. When the muscular left ventricle contracts, the blood is pumped throughout the body. When the right atrium expands, the deoxygenated blood in the body comes to the upper chamber of the right atrium. As the right atrium contracts, the corresponding lower chamber i.e., right ventricle dilates on the left i.e., on the left atrium. This left atrium relaxes while receiving this blood. After this, this left atrium contracts and the next chamber i.e., left ventricle expands so that the blood is transferred to the lungs for oxygenation. Ventricles pump the blood into various organs. Hence, they have thicker musuclar walls than the atria