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9. Transport eLearn.Punjab

Right atrium receives deoxygenated blood from body via the main veins i.e. superior and inferior
vena cavae. When right atrium contracts it passes the deoxygenated blood to right ventricle. The
opening between right atrium and right ventricle is guarded by a valve known as tricuspid valve
(because it has 3 flaps). When right ventricle contracts, the blood is passed to pulmonary trunk,
which carries blood to lungs. Tricuspid valve prevents the backflow of blood from right ventricle
to right atrium. At the base of pulmonary trunk, pulmonary semilunar valve is present which
prevents the backflow of blood from pulmonary trunk to right ventricle.

The walls of left ventricle are the thickest one. These are about a half-inch thick. They have enough force
to push blood into the body. This gives an evidence that the structures of the parts of heart are adaptive

to their functions.

The oxygenated blood from lungs is brought by pulmonary veins to left atrium. Left atrium
contracts and pumps this blood to left ventricle. The opening between left atrium and left ventricle
is guarded by a valve known as bicuspid valve (because it has two flaps). When left ventricle
contracts, it pumps the oxygenated blood in aorta, which carries blood to all parts of body (except
lungs). Bicuspid valve prevents the backflow of blood from left ventricle to left atrium. At the base
of aorta, aortic semilunar valve is present which prevents the backflow of blood from aorta to
left ventricle (Figure 9.15).

Animation 9.8 : Blood flow V: 1.1
Source & Credit: thomascsherman

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