c20 - BIOLOGY 2402 Anatomy and Physiology Lecture CHAPTER...

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BIOLOGY 2402 Anatomy and Physiology Lecture CHAPTER 20 THE CARDIOVASCULAR SYSTEM: THE HEART
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THE CARDIOVASCULAR SYSTEM: THE HEART Cardiology – Is a medical specialty concerned with the diagnosis and treatment of heart disease. Cardiovascular System (the heart, blood vessels, and blood). The heart is the center of the cardiovascular system. (The heart propels blood through an estimated 100,000km (60,000mi) of blood vessels). (At rest, pumps 30 times its own weight per minute - about 5 liter (5.3 qt) to the lungs and the same volume to the rest of the body). (At rest, the heart would pump more than 14,000 liters (3,600 gal) of blood in a day or 10 million liters (2.6 million gal) in a year). OVERVIEW OF THE CIRCULATION The heart, with each beat, pumps blood into two close circuits: (1) Systemic circulation (2) Pulmonary circulation 1. Systemic Circulation - The left side of the heart is the pump for the systemic circulation. Receives freshly oxygenated blood from the lungs and propel it into the largest artery in the body , the aorta - then to smaller systemic arteries - then to arterioles - and then to capillary . Through thin capillary walls , exchange of nutrients and gases occur. Blood unloads oxygen (O 2 ) and picks up carbon dioxide (CO 2 ). Capillary conects to venule . Venules carry deoxygenated (oxygen-poor) blood away from tissues
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and merge to form large veins , takes blood towards the heart. 2. Pulmonary Circulation - The right side of the heart is the pump for the pulmonary circulation. Receives all deoxygenated blood returning from the systemic circulation. Blood ejected from the right side of the heart flows into the pulmonar trunk - that branches into pulmonary arteries - carries blood to the right and left lungs . In pulmonry capillaries , blood picks up oxygen and unloads carbon dioxide, which is exhaled. Fleshly oxygenated blood then returns to the left side of the heart to begin another pass through the systemic circulation. LOCATION AND SIZE OF HEART - Situated between the lungs in the mediastinum (the mass of tissue between the lungs that extends from the sternum to the vertebral column). Rest on the Diaphragm, near middle of thoracic cavity. - Contains four chambers: (a) two atria , and (b) two ventricles . - About two thirds (2/3) of the mass of the heart lies to the left of the body's midline. A space called Mediastinum. - Shaped like a blunt cone about the size of your closed fist - 12 cm (5 in) long , 9 cm (3 1/2 in) wide at its broadest point, and 6 cm (2 1/2 in) thick. - Apex is the pointed inferior of the heart formed by the tip of the left ventricle and tilts obliquely toward the left hip.
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- Base is opposite the apex, the wide superior and posterior margin of the heart, formed by the atria (mostly the left atrium) so named because it is broad and rather flat, like the base of a pyramid. * Heart is a hollow, muscular organ:
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This note was uploaded on 04/07/2008 for the course BIOL 2402 taught by Professor Imo during the Spring '08 term at University of St. Thomas-Texas.

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c20 - BIOLOGY 2402 Anatomy and Physiology Lecture CHAPTER...

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