15 Cv Cycle

15 Cv Cycle - CARDIAC CYCLE page 1 AC Brown A7b HEART AS A...

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CARDIAC CYCLE AC Brown page 1 A7b HEART AS A PUMP A. Functional Anatomy of the Heart 1. Two pumps, arranged in series a. right heart : receives blood from the systemic circulation (via the great veins and vena cava) and pumps blood into the pulmonary circulation (via the pulmonary arteries) b. left heart : receives blood from the pulmonary circulation (via the pulmonary veins) and pumps blood into the systemic circulation (via the aorta) 2. Chambers: each side has two chambers a. atrium : receives blood from the veins and ejects blood into the ventricle through an A-V (atrio-ventricular) valve b. ventricle : receives blood from the atrium and ejects blood into the arterial system through a semilunar valve (ventricles responsible for most of the pumping action of the heart) 3. Valves AV Semilunar right tricuspid pulmonic l e f t mitral aortic broad smaller low resistance resist high back pressure Note: The left and right sides of the heart must pump exactly the same volume of blood when averaged over a period of time
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CARDIAC CYCLE AC Brown page 2 A7b HEART AS A PUMP (continued) B. Imparting Energy to the Blood 1. Mechanism: longitudinal shortening of myocardial fibers compresses blood in the chamber, raising pressure and causing ejection R = right ventricle (thin free wall) L = left ventricle (thick walls) S = intraventricular septum C. Valve and Papillary Muscle Function 1. Role of the valves a. impart a direction to the circulation by closing when downstream pressure exceeds upstream pressure, thus preventing backward regurgitation Note: a valve that permits regurgitation is termed incompetent or insufficient b. present a low resistance to forward flow by opening when upstream pressure exceeds downstream Note: a valve that cannot open completely and therefore presents an appreciable resistance to forward flow is termed stenotic
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This note was uploaded on 01/03/2012 for the course BIO 308 taught by Professor Acbrown during the Spring '10 term at Portland.

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15 Cv Cycle - CARDIAC CYCLE page 1 AC Brown A7b HEART AS A...

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