The Human Heart :: essays research papers

AbstractDorlands Illustrated Medical Dictionary defines the heart as "the viscus of cardiac muscle that maintains the circulation of the line". It is divided into four cavities two atria and two ventricles. The go away 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 receives the blood after it has passed through the tissues and has given up much of its oxygen. The blood then passes through the right ventricle into the lungs where it gets oxygenated. There are four major valves in the heart the left atrioventricular valve (also known as the mitral or bicuspid valve), the right atrioventricular valve (tricuspid), aortic valve, and the pulmonary valve. The heart tissue itself is nourish by the blood in the coronary arteries.2Position of the Heart Within the BodyThe heart is placed obliquely in the chest. The two atria are directed upwardly and backwards to the right and are at the take aim of the fifth through the eight dorsal vertebrae. The apex of the heart points downwards and forwards to the left and corresponds to the interspace surrounded by the fifth and sixth ribs, two inches below the left nipple. Its atrial border corresponds to a line drawn across the sternum on a level with the speeding border of the third costal cartilage. Its lower border (apex) corresponds to a line drawn across the lower end of the same bone, near the xiphoid process. Its upper surface is rounded and convex, directed upwards and forwards, and formed mainly by the right ventricle and part of the left ventricle. The posterior surface of the heart is form and rests upon the diaphragm muscle. Of its two borders, the right is the longest and thinnest, the left is shorter but thicker and round.SizeIn an adult, the heart measures about five inches in length, three and a half inches in the broadest part of its transverse diameter, and two and a half inches in its antero-posterior. The average encumbrance in the male varies from ten to twelve ounces. In the female, the average weight is eight to ten ounces. The heart will continue to grow in size up to an advanced period of life. This growth is more obvious in men than in women.3Circulation of Blood in an AdultThe heart is subdivided by a longitudinal muscular septum into two lateral halves which are named right and left according to their position.