Chapter 50 Circulation (1)

Chapter 50 Circulation (1) - Circulatory systems Metabolic...

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Circulatory systems Vertebrate circulatory systems The human heart The vascular system: arteries, capillaries, and veins Blood Control and regulation of circulation Metabolic needs of cells of large animals are served by a circulatory system that transports nutrients , respiratory gases , and metabolic wastes throughout the body and must adjust to changing metabolic rates. The lecture will cover
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Vertebrate systems The vertebrate heart evolved from two chambers in fishes to three chambers in amphibians and reptiles and four chambers in crocodilians, mammals, and birds. This progression has led to an increasing separation of blood flow to the gas exchange organs and to the rest of the body. For example, in fish, blood is pumped from the heart to the gills to the tissues and back to the heart. In birds and mammals, blood is pumped from the heart to the lungs, back to the heart ( pulmonary circuit), and then from the heart to the tissues and back to the heart ( systemic circuit). Note: Extracellular fluid (25%) includes blood volume (5%) and interstitial fluid (20%). For a 60 kg person, that 3 liters of blood plasma.
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2 chambered heart in fish Fish : Two chambered heart (1 atrium, 1 ventricle) The high resistance of the gas exchange organ, the gills, lie between the heart and the tissues, so oxygenated blood (blue) entering the aorta is under low pressure, limiting the ability of the system to increase blood flow to the tissues.
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One atrium receives deoxygenated blood (blue) from the body. The other receives oxygenated blood (red) from the lungs. Some mixing occurs in the single ventricle. The high resistance of the gas exchange organ is no longer between the heart and the body, so the aorta delivers blood at higher pressure than in the fish. 3 chambered heart in amphibian
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4 chambered heart in With complete separation of the left and right sides, the left side can deliver blood at high pressure to the systemic circulation, while the right side delivers blood at lower pressure to the pulmonary circulation. Oxygenated and deoxygenated blood do not mix. The systemic circuit receives (red) blood with the highest O 2 content. The lungs receive blood with the lowest O 2 and highest CO 2 content. Valves prevent backflow of blood: Atrioventricular valves lie between the atria and ventricles and prevent backflow when ventricles contract. The pulmonary valve and aortic valve lie between the ventricles and the major arteries and prevent backflow when ventricles relax.
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vessels The superior vena cava brings deoxygenated blood from the upper body to the heart. The aorta is the artery through which the left ventricle pumps oxygenated blood out to the body. The
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This note was uploaded on 04/19/2011 for the course LS 2 taught by Professor Pires during the Spring '08 term at UCLA.

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Chapter 50 Circulation (1) - Circulatory systems Metabolic...

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