IMG_NEW_0005_001 - and right sides of the ventricle Mammals...

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' Oxygenated blood sent to organs and tissues Disadvantage: blood pressure drops significantly at capillary beds (branching results ina drop in velocity and pressure): circulation rates fall and exchanges are slower . Pressure of blood leaving gills is lower than that PumPed at heart . Circulation rates may be increased by active movement of skeletal muscles during swimming Anrolribiam: . One ventricle ind two atria (3 chambers) . Blood sent to the lungs for oxygenation and returns to the heart before being PumPed to rest of the bodY Advantage over fish: . Higher delivery Pressure and circulation rate to tissues because of double circulation Disadvantage: ' Mixing of oxYgenated and deoxYgenated blood Rcstiles: ' One ventricle and two atria (3 chambers) . Blood sent to the lungs for oxygenation and returns to the heart before being pumped again to the rest of the body' ' Most reptiles' except crocodiles' have 3-chambered hearts . Varying degrees of seParation occurring between the left
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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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