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The heart is situated inside the [[thorax]] in vertebrates, and in the human body is slightly to the left. The human heart consists of 4 main chambers, 2 [[atrium|atria]] and 2 [[ventricle]]s. The right side of the heart receives de-oxygenated blood from other parts of the body and pumps it to the lungs where it is oxygenated and returns to the left side of the heart. The left side of the heart pumps the oxygen-carrying blood to the rest of the body. A heartbeat is a single pumping cycle of the heart which comprises three major stages: atrial systole, ventricular systole and complete cardiac diastole.  

The heart is situated inside the [[thorax]] in vertebrates, and in the human body is slightly to the left. The human heart consists of 4 main chambers, 2 [[atrium|atria]] and 2 [[ventricle]]s. The right side of the heart receives de-oxygenated blood from other parts of the body and pumps it to the lungs where it is oxygenated and returns to the left side of the heart. The left side of the heart pumps the oxygen-carrying blood to the rest of the body. A heartbeat is a single pumping cycle of the heart which comprises three major stages: atrial systole, ventricular systole and complete cardiac diastole.  

The right and left coronary arteries branch off the aorta and then divide into smaller branches, supplying all portions of the heart with blood and oxygen. In order for the heart to function properly, it must receive a continuous supply of fresh oxygen-enriched blood. The coronary arteries surround the heart and carry the blood which nourishes the heart muscle. The right coronary artery supplies blood to the right and back sides of the heart. The left coronary artery divides into two main branches--the circumflex and the left anterior descending--supplying blood to the left side of the heart.

The right and left coronary arteries branch off the aorta and then divide into smaller branches, supplying all portions of the heart with blood and oxygen. In order for the heart to function properly, it must receive a continuous supply of fresh oxygen-enriched blood. The coronary arteries surround the heart and carry the blood which nourishes the heart muscle. The right coronary artery supplies blood to the right and back sides of the heart. The left coronary artery divides into two main branches—the circumflex and the left anterior descending—supplying blood to the left side of the heart.

There are four heart valves. They are all one-way valves to keep blood moving through the various chambers of the heart.

There are four heart valves. They are all one-way valves to keep blood moving through the various chambers of the heart.

Abnormal heartbeats, called arrhythmia, or slower or faster heartbeats, called bradycardia and tachycardia, respectively, are dangerous medical conditions which often appear as a result of an underlying condition. One of these is disorders is sudden arrhythmic death syndrome, or SADS. SADS is a condition caused by a hereditary genetic defect which can be triggered by high heart rates (from exercise, for example) or extreme emotional distress. As a result, people with the defect who may be otherwise young and healthy have been known to simply and unexpectedly "drop dead". The condition can be treated with a defibrillator implant, however it is not usually detected until the subject has been observed to have an attack, and such attacks are usually fatal.

Abnormal heartbeats, called arrhythmia, or slower or faster heartbeats, called bradycardia and tachycardia, respectively, are dangerous medical conditions which often appear as a result of an underlying condition. One of these is disorders is sudden arrhythmic death syndrome, or SADS. SADS is a condition caused by a hereditary genetic defect which can be triggered by high heart rates (from exercise, for example) or extreme emotional distress. As a result, people with the defect who may be otherwise young and healthy have been known to simply and unexpectedly "drop dead". The condition can be treated with a defibrillator implant, however it is not usually detected until the subject has been observed to have an attack, and such attacks are usually fatal.

A [[Myocardial infarction|myocardial infarction]], more commonly known as a heart attack, occurs when the blood vessels which supply the hearts muscle tissue become partially or totally blocked.  Heart attack is the number one cause of death in America.

A [[myocardial infarction]], more commonly known as a heart attack, occurs when the blood vessels which supply the hearts muscle tissue become partially or totally blocked.  Heart attack is the number one cause of death in America.

 

 

 

 

It is the universal symbol of [[love]] and the heart is also called a Valentine.

It is the universal symbol of [[love]] and the heart is also called a Valentine.

In the [[Bible]], the heart is a metaphor for the seat for our deepest emotions and wishes, and for the seat of [[sin]]. <ref>http://www.bible.org/page.php?page_id=858.# The seat of Sin, the heart</ref>

In the [[Bible]], the heart is a metaphor for the seat for our deepest emotions and wishes, and for the seat of [[sin]].<ref>http://www.bible.org/page.php?page_id=858.# The seat of Sin, the heart</ref>

== See Also ==

== See also ==

*[[Heart attack]]

*[[Heart attack]]

*[[Mitral regurgitation]]

*[[Mitral regurgitation]]

== references ==

== References ==

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[[Category:Anatomy]]

[[Category:Anatomy]]