Biology - Histology The Human Heart. Abstract: Dorland's Illustrated Medical Dictionary defines the heart as "the viscus of cardiac muscle that maintains the circulation of the blood". It is divided into four cavities; two atria and two ventricles. The left atrium receives oxygenated blood from the lungs. From there the blood passes to the left ventricle, which forces it via the aorta, through the arteries to supply the tissues of the body. The right atrium …showed first 75 words of 3471 total…

…showed last 75 words of 3471 total…systole.6,2,&4 Summary: The heart is arguably the most vital organ the human body possesses. Without the heart, none of the tissues in the body would receive the vital oxygen necessary for them to maintain survival. Heart disease is the number one killer of people in America today. Due to this disturbing fact, it is no wonder such a large percentage of the fellowships granted by the National Institutes of Health go towards heart related illnesses.