Anatomy of the Heart

The heart is the muscular pump that is located between your lungs, slightly to the left of your breastbone. It is slightly larger than a human fist, with a weight of between 200 to 425 grams. Everyone’s heart has to beat approximately 100,000 times each and every day.

The Anatomy of the Heart with labels

The Anatomy of the Heart

Your heart comprises of four chambers, the upper chambers are referred to as the left and right atria, collectively called the atrium, whilst the lower chambers are called the right and left ventricle. A wall of muscle known as the septum separates the four chambers.

The largest of the chambers is the left ventricle, as they have to force the blood through the aortic valve into the body. The right side of the heart is small because it only has to transmit blood a short distance to the lungs.

The heart itself is merely a pump which contracts and relaxes, in the cardiac cycle. The coronary arteries feed the oxygen, and the nutrients to the heart muscles, which need it to function effectively. The two coronary arteries, exit the heart through the aorta. The left main coronary artery is less than an inch long and very thin; it later branches into two smaller arteries, which themselves branch into arteries of decreasing size. The smaller vessels are capable of penetrating the heart muscle. The capillaries are so tiny that the red blood cells can only travel in single file. The functions of these tiny blood vessels is to transfer oxygen and nutrient filled blood to the cardiac muscles, and then take the waste products such as carbon dioxide away for effective disposal by lungs, kidney’s and the liver.

The superior and inferior vena cava are the two main veins which bring the deoxygenated blood to the heart, and they empty into the right atrium. The veins from the upper torso and head empty in the superior, and the veins from the legs and lower torso feed into the inferior vena cava.

The aorta is the largest of the body’s blood vessels, being about the diameter of the thumb, and carries the reoxygenated blood from the largest heart chamber the left ventricle to the body.

The deoxygenated blood is taken from the right ventricle to the lungs, by the pulmonary artery. Arteries carry blood away from the heart, but it not always reoxygenated. Conversely veins carry blood towards the heart, and it is the pulmonary vein, which carries the oxygen rich blood from the lungs to the left atrium. At this time the left atrium is contracting and forcing the oxygenated blood through the mitral valve into the left ventricle. When the ventricle is full of blood it contracts and forces the aortic valve open and the mitral valve closes. This action causes the blood to be pumped into the left atrium. The mitral valve closes to prevent a back flow of the blood and the blood exits the heart through the aorta. The tricuspid valve separates the right atrium from the right ventricle, and assists the blood to flow through.

As the right ventricle receives the blood the right atrium contracts, which makes the ventricle fill, when this process is complete the right ventricle contracts forcing the tricuspid valve to close. The increases pressure opens the pulmonary valve to open and the blood to flow through the pulmonary artery, which transports the blood to the lungs.

GLOSSARY OF TERMS

Septum,

The wall of muscle separating the upper and lower levels of the heart.

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