THE HUMAN HEART AND ITS
FUNCTIONS
ADD BY ABBU IZHAR
The human heart is a hollow pear-shaped muscular organ located between the lungs in the middle of
your chest. It is responsible for pumping blood through your body, supplying the cells and tissues with
oxygen and nutrients. In order to meet your body’s energy demands your heart must beat more than
1, 00,000 times per day.
Like all of the other tissue of the body, your heart also needs oxygen and nutrients in order to
function properly. The blood flowing through the heart is traveling too fast for the heart to absorb, so
the heart has its own system of vessels, called the coronary arteries that supply it with oxygen and
nutrients.
Inside your heart are four chambers. The upper chambers are called atria. They are very small, holding
only about three and half tablespoons of blood at a time, the lower chambers are called ventricles.
They are slightly larger than the atria, holding about a quarter of a cup of blood at a time. It is amazing
that these small chambers are responsible for pumping a total 2000 gallons of blood per day.
In the upper part of the right atrium is a small patch of special heart tissue called the sinoatrial node. It is
the heart’s pacemaker and is responsible for triggering and establishing your heartbeat.
This small patch of tissue tells your heart to speed up when you are running or exercising
and to slow down when you are sitting or sleeping.
Each half of your heart works as a separate circulatory pump. The right side of the heart is
responsible for returning the oxygen-poor blood to the lunge to expel carbon dioxide and
be re-oxygenated. The right chamber of the heart receives blood from the vena cava. The
blood is then pushed through the tricuspid valve-into the right ventricle. When the right
ventricle contracts, the blood rushes in to the pulmonary artery and in to the lungs. The
pulmonary artery is the only artery in your body that carries oxygen-poor blood.
The left side of your heart receives the newly oxygenated blood from your lungs and
pumps it through your entire body. The oxygenated-rich blood enters the left atrium
through the four pulmonary veins. The pulmonary veins are the only veins in your body
that carry oxygen-rich blood. From the left atrium, the blood flow to the left ventricle is
controlled by the mitral valve. The wall of the left ventricle is three times thicker than the
walls of the right ventricle. The thickness of the cardiac muscle gives the left ventricle the
power needed to pump the blood through your entire body, from head to toe and back.
As your heart contrast the blood is pushed through the aortic semi lunar valve into the
aorta, your body’s largest blood vessel, and is distributed through your body via a network
of arteries.