Unformatted text preview: and right sides of the ventricle Mammals andbirds: . Have evolved the 4-chambered heart . Endothermy requires higher oxygen delivery to tissues . Evolved the 4-chambered heart bY convergence to satisfy this requirement . Double circulation separates deoxygenated from oxygenated blood Two results: 1. lncreases the efficiency of oxygen delivery to the tissues and 2. Maintains good delivery pressure and circulation rate 4. Coordinated cycles of heart contraction drive double circulation in mammals All components of the cardiovascular system function together to meet the body's continuous (but highly variable) demand for 02 Mammal circulation overview Fig' 42'6 Cardiac cYcle 0.8 sec @ 72 bPm Systole = contraction Phase Diastole = relaxation Phase Maintaining the heart's rhythmic beat during the cardiac cYcle (Fig' 42'9) 5. Blood vessels consist of arteries and veins Blood vessel structure and function Fig' 42'tO...
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- Fall '10
- double circulation, circulation rate, circulation overview Fig