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A Estrutura de Paredes Heart

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    Brian W.
    GB
    Brian W.

    the walls of the chambers of the heart are made up of three layers, the outer wall is called the epicardium( also known as the visceral pericardium). The middle layer is the myocardium and the inner wall is called the endocardium. The chambers of the heart themselves are lined with a simple epithelium known as endocardium, likewise ,the epicardium is a simple epithelium tissue, which surrounds the outside of the heart. The most important of the three layers is the myocardium, the middle layer, it is made up of cardiac muscle tissue. cardiac muscle tissue consists of fibres formed by fusion of many individual cells (syncytium), these fibres are striated and branched. The myocardium is thicker in the walls of the ventricles then the atria, this is because the greater pressures are needed for the ventricles to perform their functions. The wall of the left ventricle is especially thick as it has to drive the blood throughout the body. The inner surfaces of the ventricular walls have ridges of muscle known as the trabeculae carneae with spaces between them . When the musculature with in the chamber wall contracts, the lumen decreases ( the cavity) decreases in diameter, this is particularly true in the left ventricular. There is also a twisting or wringing action of the left ventricle that causes the apex of the heart to hit against the inner surface of the chest wall, the 'apex beat The stroke volume is the amount of blood forced out of each ventricle in one contraction. The cardiac output is the volume of blood pumped out of the ventricles ( right into the lungs ,left into the systemic circulation) in one minute ( litres per minute).The volumes will change due to the bodies needs.

    Brian W.
    GB
    Brian W.

    The heart has it's own oxygen supply, is it because it has to work so hard continually, what is the average time that the heart beats per minute.

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