Answer
The heart of
mammal has 4 chambers:left atrium,right atrium,left ventricle and right
ventricle.Both atria walls are thin,but the left and right ventricles have
thick muscular wall that can contract strongly to pump blood out of the
heart.Walls of the left ventricle are 3-4 times thicker than the left ventricle
has to pump blood through the whole body,while the right ventricle pumps blood
into the lungs only.The left side of the heart is completely separated from the
right side by the intraventricular septum.Atrium receives and collects blood
from the body and lungs,which is then channeled into the ventricle.The right
atrium receives deoxygenated blood from the body via the superior vena cava.The
left atrium receives oxygenated blood from the lungs via the pulmonary
vena.From the right atrium,blood enters the right ventricle through the
tricuspid valve.Blood is then pumped from the right ventricle to the lungs,the
left pulmonary artery transport blood to the left lung and right pulmonary
artery transport blood to the right lung.Pulmonary artery is the only artery
carrying deoxygenatedblood.All the other arteries transport blood rich in
oxygen.When the right ventricle contracts,blood is prevented from re-entering
the right atrium by the tricuspid valve.Blood enriched with oxygen in the lungs
is channeled by left and right pulmonary veins into the left atrium.Pulmonary
veins are the only veins in the body transporting oxygenated blood.Blood is
pumped from the left atrium into the left ventricle.Contraction of the left
ventricle wall forces the blood out to every part of our body via the
aorta.Blood is prevented from flowing back into the left atrium by the bicuspid
valve.Semi-lunar valves prevent blood from flowing back into the ventricles
from the pulmonary artery or aorta.
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