experiment of internal and external features of heart
Answers
Answer:
Layers of the Heart
The heart wall consists of 3 layers:
Epicardium: thin external layer formed by visceral layer of serous pericardium
Myocardium: thick middle layer made of cardiac muscle
Endocardium: thin internal membrane that lines the heart and its valves. It is composed of endothelium and sub-endothelial connective tissue, similar to intimal component of blood vessels.
External Features
The heart and roots of great vessels are embedded in the pericardial sac, approximately in the center of the thorax. The size of the heart is slightly larger than a clenched fist. The heart is surrounded laterally and posteriorly by the lungs, and anteriorly bound by the sternum and medial sections of the ribs and sterno-costal joints.
It has the shape of a three-sided pyramid with an apex (left anterior), a base (posterior), and 4 surfaces: Sterno-costal/anterior (formed by right ventricle), diaphragmatic/inferior (formed by left ventricle and part of right ventricle), left pulmonary (formed by left ventricle, in contact with left lung), and right pulmonary (formed by right atrium).
The heart appears trapezoid in the posterior and anterior views. As such, it consists of 4 borders: Right (convex), Inferior (horizontal), left (oblique), and superior.