Monday, April 21, 2014

BIOLOGY: HUMAN HEART

The human heart is a vital organ that functions as a pump, providing a continuous circulation of blood through the body, by way of the cardiac cycles. The heart is contained in the mediastinum in the thoracic cavity of the thorax.
The heart is enclosed in a protective sac, the pericardium which also contains a lubricating pericardial fluid. The outer wall of the heart is made up of three layers, the epicardium, the myocardium which is the muscle of the heart, and the endocardium. The heart is divided into four main chambers: the two upper chambers are called the left atrium and the right atrium (plural atria) and the two lower chambers are called the right and the left ventricle. There is a dividing wall of muscle the septum which separates the right side of the heart from the left side of the heart. The part of the septum that separates the ventricles, the ventricular septum is thicker than that which separates the atria, the atrial septum.
Normally with each heartbeat, the right ventricle pumps the same amount of blood into the lungs that the left ventricle pumps out into the body. Physicians commonly refer to the right atrium and right ventricle together as the right heart and to the left atrium and left ventricle as the left heart.
The human heart and its disorders (cardiovascular diseases) are studied primarily by cardiologists.

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