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rav65819_ch49_983-1016 - concept outline 49 49.1...

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;;;;;;;;;;;;;; concept outline 49 49.1 Invertebrate Circulatory Systems Open circulatory systems move fluids in a one-way path Closed circulatory systems move fluids in a loop 49.2 Vertebrate Circulatory Systems In fishes, more efficient circulation developed concurrently with gills In amphibians and most reptiles, lungs required a separate circulation Mammals, birds, and crocodilians have two completely separated circulatory systems 49.3 The Four-Chambered Heart and the Blood Vessels The cardiac cycle drives the cardiovascular system Arteries and veins branch to and from all parts of the body Arterial blood pressure can be measured Contraction of heart muscle is initiated by autorhythmic cells 49.4 Characteristics of Blood Vessels Larger vessels are composed of four tissue layers Arteries and arterioles have evolved to withstand pressure Capillaries form a vast network for exchange of materials Venules and veins have less muscle in their walls The lymphatic system is an open, one-way system Cardiovascular diseases affect the delivery system 49.5 Regulation of Blood Flow and Blood Pressure The nervous system may speed up or slow down heart rate Cardiac output increases with exertion The baroreceptor reflex maintains homeostasis in blood pressure Blood volume is regulated by hormones 49.6 The Components of Blood Blood plasma is a fluid matrix Formed elements include circulating cells and platelets Formed elements arise from stem cells
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Blood clotting is an example of an enzyme cascade 49.7 Gas Exchange Across Respiratory Surfaces Gas exchange involves diffusion across membranes Evolutionary strategies have maximized gas diffusion 49.8 Gills, Cutaneous Respiration, and Tracheal Systems External gills are found in immature forms of fish and amphibians Branchial chambers protect gills of some invertebrates Gills of bony fishes are covered by the operculum Cutaneous respiration requires constant moisture Tracheal systems are found in arthropods 49.9 Lungs Breathing of air takes advantage of partial pressures of gases Lungs of amphibians and reptiles are specialized outgrowths of the gut Mammalian lungs have greatly increased surface area The respiratory system of birds is a highly efficient flow-through system Lung structure and function supports the respiratory cycle Ventilation efficiency depends on lung capacity and breathing rate Ventilation is under nervous system control Respiratory diseases restrict gas exchange chapter The Circulatory and Respiratory Systems introduction EVERY CELL IN THE ANIMAL BODY must exchange materials with its surrounding environment. In single-celled organisms, this exchange occurs directly across the cell membrane to and from the external environment. In multicellular organisms, however, most cells are not in contact with the external environment and must rely on specialized systems for transport and exchange. Although
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