In the previous lesson, ( to see the first lesson on circulatory system click here) we studied the structure of the main blood vessels and heart. In this lesson we will study in detail how the heart supplies blood to the body.
Process:
Deoxygenated blood is received by the heart from the main vein called vena cava. There are two vena cava; superior and inferior. Superior vena cava receives the blood from the upper body such as the brain and inferior vena cava brings the blood from the lower part of the body such as legs. They enter in the right atrium and then right ventricle through a tricuspid valve which is in between the right atrium and right ventricle. This valve stops the backflow of blood and helps it to move efficiently.
Then from the right ventricle, blood moves into the pulmonary artery which has semilunar valves which helps the blood to move forward and prevents the backflow of blood into the right ventricle. Blood then flows to the lungs, capillaries in the lungs are around the air sacs which are known as alveoli. Blood in these capillaries absorbs oxygen and releases carbon dioxide, (the process of exchange of gases in air sacs will be discussed in the respiratory system). Then this blood comes back to the heart through a vein known as pulmonary vein. This is the only vein which brings oxygenated blood and pulmonary artery is the only artery which carries away deoxygenated blood.
Blood then comes to the left atrium and moves in the left ventricle, which has the strongest muscles. In between the left atrium and left ventricle, bicuspid valves exist. Over here, pressure is very high, so the semilunar valves of the aorta open and blood moves into the aorta with high pressure. Aorta is the main artery which supplies the blood to other parts of the body. The semilunar valve closes as soon as the pressure decreases, to prevent the backflow of blood into the left ventricle.
*All pictures are taken from google*
Comments