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In a healthy heart, blood flows one way through the heart due to heart valves, which prevent backflow. [4] The heart is enclosed in a protective sac, the pericardium, which also contains a small amount of fluid. The wall of the heart is made up of three layers: epicardium, myocardium, and endocardium. [8]
Illustration depicting the layers of the heart wall including the innermost endocardium. The endocardium (pl.: endocardia) is the innermost layer of tissue that lines the chambers of the heart. Its cells are embryologically and biologically similar to the endothelial cells that line blood vessels. The endocardium also provides protection to the ...
The heart is a muscular organ situated in the mediastinum.It consists of four chambers, four valves, two main arteries (the coronary arteries), and the conduction system. The left and right sides of the heart have different functions: the right side receives de-oxygenated blood through the superior and inferior venae cavae and pumps blood to the lungs through the pulmonary artery, and the left ...
In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. [1] [2] It includes the cardiovascular system, or vascular system, that consists of the heart and blood vessels (from Greek kardia meaning heart, and Latin vascula meaning vessels).
Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscle tissues, the others being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that constitutes the main tissue of the wall of the heart .
The pericardium (pl.: pericardia), also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. [1] It has two layers, an outer layer made of strong inelastic connective tissue (fibrous pericardium), and an inner layer made of serous membrane (serous pericardium).
The trabeculae carneae and the papillary muscles make up a significant percentage of the ventricular mass in the heart (12-17% in normal human adult hearts), and are correlated with ventricular end diastolic volume. [5] Trabeculae ratios of capillary-to myocyte differ between the walls of the right and left ventricle.
In most fish, the circulatory system is very simple: a two-chambered heart including one atrium and one ventricle. Among sharks, the heart consists of four parts arranged serially: blood flows into the most posterior part, the sinus venosus, and then to the atrium which moves it to the third part, the ventricle, before it reaches the conus ...