Tips For Heart Month: How Your Heart Works
"Oh, wondrous power! How little understood...to fashion genius,
form the soul for good." -- Sarah J. Hale Your heart is a
beautifully designed pump whose purpose is to deliver blood,
together with life-giving oxygen and nutrients, to every cell,
tissue, and organ of your body. Shaped like a pear and weighing
about eleven ounces, the heart sits in the center of the chest,
pointing up toward the right shoulder. It is a specialized
muscle divided into four chambers, two on the right and two on
the left, which are separated by one-way valves. The heart
therefore is in a sense two pumps, because it's right and left
sides are separated from each other.
There are four chambers in the heart, two--an atrium and a
ventricle--on either side. The right atrium is a receptacle for
the veins transporting blood back into the heart. When it has
filled, the chamber's muscle contracts and empties its contents
through the tricuspid valve and into the right ventricle.
The right ventricle transports oxygen-depleted blood to the
lungs across the pulmonary valve and into the pulmonary artery
and its branches. The blood travels into progressively smaller
arteries and eventually into tiny vessels called capillaries.
These vessels have very thin and delicate linings that allow
oxygen and other nutrients to move into and out of the
bloodstream. The oxygen in the lungs moves across the capillary
membranes and into the blood, where it hooks up with the red
blood cells. The capillaries also eliminate carbon dioxide,
received from the tissues and cells of the body, to the lungs
where it is exhaled into the atmosphere.
Once these exchanges have been completed, the blood moves
through the pulmonary vessels to the left side of the heart. The
left atrium is the collecting chamber. Once it is full, the left
atrium moves its contents across the mitral valve into the left
ventricle.
The left ventricle is by far the most powerful pumping chamber
of the heart. Its contents must be propelled under pressure much
higher than in the other chambers, so the oxygen-enriched blood
can travel through the arteries of the body at a sufficient
pressure to reach every cell and organ. Its powerful thrust
sends blood through the aortic valve and into the aorta, the
largest artery in the body. From there the blood continues
flowing to the arteries.
This extraordinary round-trip takes about a minute and repeats
itself every minute of your life. In an average person's
lifetime, it is estimated that the heart contracts 2.5 billion
times! Each day, the average heart beats some 100,000 times and
pumps more than 2,000 gallons of blood through the equivalent of
approximately 60,000 miles of blood vessels! Your heart is a
mighty organ indeed!