the heart

Essay by mwachofi May 2014

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The heart is a hollow muscular, cone-shaped organ that controls the flow of blood in the body. It is usually located on the level of the fifth intercostals space about 9 cm from the midline. The heart measure about 10 cm /4 inch long and is about the size of the owner's first.

General Structure of the Heart

The heart is composed of three layers of tissues.

The pericardium:

The pericardium is the outer part that covers the heart and consists of two layers; the outer fibrous pericardium is securely attached to the diaphragm, the outer coat of the great vessels and the posterior surface of the sternum and therefore maintains the heart in its position. Its fibrous nature prevents over distension of the heart.

The inner layer the serous pericardium consists of two layers the outer or parietal layer lines the outer fibrous sac and the inner or visceral layer covers the heart muscle.

The serous membrane secretes serous fluid into the space between the visceral and parietal layers that allows smooth movement between the layers, when the heart beats.

The Myocardium:

The myocardium is the middle layer of the heart and is composed of specialized muscle tissue called as the cardiac muscle, on which the circulation of blood depends. It varies in thickness, being thickest in the left ventricle, thinner in the right ventricle and thinnest in the artrium.

The Endocardium:

The Endocardium forms the inner lingning of the heart is a thin, smooth, glistening membrane consisting of flattened epithelial cells which is continuous with the valves and with the lining of the blood vessels.

Interior of the Heart

The heart is divided into a right and left side by a muscular partition called as the septum. Each side is subdivided into an upper and lower...