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1 Exchange in Animals • Diffusion is slow Animal Circulation Lecture 13 Winter 2014 Strategy • Most cells in direct contact with environment • What would these animals look like? Fig. 40.3 2 Exchange in Animals No distinct circulatory system • Sponges Exchange in Animals • Strategy - Water vascular system – Network of water filled canals, for gas exchange, waste disposal, and movement – No gastrovascular cavity • Cnidarians & flatworms – Gastrovascular cavity • Digestion & distribution of substances throughout body Fig. 42.2 Fig. 33.40 3 Exchange in Animals 4 Circulatory Systems Strategy - Circulatory system • Transports fluids throughout the body Three components • Circulatory fluid • Interconnecting tubes • Pump (heart) – Gas exchange – Transports nutrients – Dispose of wastes Fig. 42.6 Fig. 42.3 Fig. 42.6 1 5 Open Circulatory System • Circulatory fluid bathes organs directly • Arthropods & most molluscs • Hemolymph Closed Circulatory Systems 6 • Blood confined to vessels • Blood distinct from interstitial fluid • Annelids, cephalopods (squid, octopus) & all vertebrates • High blood pressure – High energy demands – Both circulatory fluid & interstitial fluid • Lower hydrostatic pressure – Lower energy demands Fig. 42.3 Fig. 42.3 7 Cardiovascular system Cardiovascular system 8 • Atria – Receive blood into heart • Ventricles – Pump blood out of heart • Arteries & arterioles – Carry blood away from heart to capillaries • Capillaries – Microscopic; thin, porous walls – Capillary beds – Diffusion between blood & interstitial fluid • Veins & venules – Carry blood toward heart from capillaries • Portal Veins – Transport between pairs of capillary beds Fig. 42.6 Fig. 42.7 9 Single Circulation Double Circulation 10 • Two distinct circuits • Blood passes through heart once in each complete circuit • Bony & cartilaginous fish • Disadvantages? – Pulmonary & systemic – Pump for circuits combined in single organ • Pulmonary circuit – Right side of heart delivers oxygen-poor blood to lung capillaries – delivers oxygen-rich blood to heart Fig. 42.4 Fig. 42.5 2 Double Circulation 11 12 Double Circulation • Systemic Circuit – Left side of heart delivers oxygen-rich blood to body – returns oxygen-poor blood to heart • Pulmocutaneous circuit – Involves capillaries in lungs and skin • Benefits of double circulation? Fig. 42.5 Fig. 42.5 13 14 Double Circulation • Mammals & birds – convergent evolution Mammalian Circulation Fig. 42.6 Fig. 42.5 3