During the atrial systole, the openings of the pulmonary vein and the vena cava are closed. During the ventricular systole, the openings of the pulmonary artery and the aorta are open.

The intercellular fluid fills up the space between all human body cells.

The left auricle (also called left atrium) of the heart receives oxygenated blood from the lungs through the pulmonary vein.

The right ventricle of the heart pumps the blood up to the lungs only. This blood gets oxygenated in the lungs and is then pumped into the left auricle by the pulmonary vein.

The process of circulation of blood in the heart begins with the contraction of the auricles of the heart.

During the atrial systole, the atrial muscles contract.

When the auricles of the heart contract, the ventricles relax, and vice versa.

Plasma is the yellow-colored, alkaline constituent of blood.

During the ventricular systole, the blood enters the auricles. During the atrial systole, the blood enters the ventricles.

During the ventricular systole, the semilunar valves are open to allow the flow of blood into the pulmonary artery and the aorta. During the atrial systole, the semilunar valves are closed to prevent the flow of blood back into the ventricles.

In a normal adult, the red blood corpuscles are produced in the bone marrow. In an embryo, they are produced in the liver and the spleen.

The inferior vena cava (also called posterior vena cava) carries deoxygenated blood from the lower (posterior) parts of the body (e.g., abdomen, legs, etc.)

The cardiac veins collect blood from the walls of the heart.

With reference to the heartbeat, the word 'systole' refers to a contraction phase whereas the word 'diastole' refers to a relaxation phase.

The right auricle of the heart receives deoxygenated blood from all parts of the body through the vena cava. The left auricle receives oxygenated blood through the pulmonary veins.