Structure
Of The Heart
The heart is divided vertically into two cavities by a
muscular wall called the septum. The left cavity pumps
blood throughout the body, while the right cavity pumps
blood only to the lungs. Each cavity is in turn divided
horizontally into two chambers, making a total of four
chambers altogether. The two upper chambers are known
as the atria, and the two lower chambers as the ventricles.
The atria receive blood flowing back to the heart, while
the ventricles hold blood that is to be pumped out of
the heart.
The four chambers of the heart are separated by a series
of one-way flaps called valves. The tricuspid valve separates
the right atrium from the right ventricle. The bicuspid
valve, also known as the mitral valve, separates the left
atrium from the left ventricle.
In addition, there are valves separating the ventricles
from the pulmonary artery and the aorta, the two major
arteries carrying blood out of the heart. The pulmonary
valve separates the right ventricle from the pulmonary
artery which carries oxygen-poor blood from the heart
to the lungs for oxygenation. The aortic valve, on the
other hand, separates the left ventricle from the aorta
which transports oxygen-rich blood to all parts of the
body. Together, these valves ensure that blood flows in
the right direction through the heart such that it enters
via the atria, passes into the ventricles, and then exits
from either the aorta (for blood in the left ventricle)
or the pulmonary artery (for blood in the right ventricle).
To the right and left of the heart respectively lie two
major coronary arteries. These provide the heart with
the constant supply of oxygen-rich blood which it needs
to function effectively as a pump.
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