Heart - Heart Overview • The main motive force that...

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Unformatted text preview: Heart Overview • The main motive force that propels blood around the body is the heart. • The heart is a pump that creates high pressure in the aorta and in the pulmonary trunk. • The heart is actually a double pump serving two separate cardiovascular circuits. • The heart pumps continuously throughout life. Location • The heart is a fist sized organ located in the pericardial cavity. • The pericardial cavity is located in the mediastinum. • The mediastinum lies within the thoracic cavity between the two pleural cavities. • The heart is surrounded by a membrane called the pericardium. Location Pericardium • The outer portion of the pericardium is a fibrous structure that anchors the heart to the surrounding structures and prevents overfilling. • The inner portion is a serous membrane with a parietal and visceral layer. • The visceral layer is the outer layer of the wall of the heart and is called the epicardium. Wall of the Heart • Deep to the epicardium is the myocardium, or muscular wall of the heart. • The myocardium is supported by a fibrous skeleton of the heart, composed of collagen fibers. • The inner lining of the lumen of the heart is the endocardium (simple squamous epithelium), which is continuous with the endothelium of the blood vessels. Wall of the Heart Chambers of the Heart • The heart consists of four chambers; two atria and two ventricles. • The left and right atria are thin walled chambers that receive blood from the circulations. • The left and right ventricles are thick walled chambers that pump blood to the circulations. • Left and right ventricles are divided by the interventricular septum. Chambers of the Heart Atria • Each atrium has a smooth posterior wall and a ridged anterior wall. • Ridges are formed by pectinate muscles. • Blood enters right atrium from superior and inferior venae cavae and coronary sinus. • Blood enters left atrium from pulmonary veins. Ventricles • Each ventricle is lined with trabeculae carneae and papillary muscles. • Right ventricle pumps blood into the pulmonary trunk. • Left ventricle pumps blood into the aorta . • The left ventricle is larger and thicker than the right ventricle. Heart Valves • There are two sets of fibrous structures that serve as valves in the heart: – Atrioventricular (AV) valves between the atria and the ventricles. – Semilunar vavles between the ventricles and the major arteries. • Valves prevent back flow of blood during pumping. Atrioventricular Valves • The AV valves are loose valves that close during ventricular contraction. • They are anchored to the papillary muscles by the chordae tendinae. • The right AV valve has three cusps (tricuspid valve)....
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This note was uploaded on 04/15/2011 for the course BIOL 2301 taught by Professor Kasparian during the Spring '10 term at North Texas.

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Heart - Heart Overview • The main motive force that...

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