Download L13; Circulation

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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
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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
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Exchange in Animals
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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
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Open Circulatory System
• Circulatory fluid bathes
organs directly
• Arthropods & most
molluscs
• Hemolymph
Closed Circulatory Systems
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• 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
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Cardiovascular system
Cardiovascular system
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• 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
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Single Circulation
Double Circulation
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• 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
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Double Circulation
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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
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Double Circulation
• Mammals & birds – convergent evolution
Mammalian
Circulation
Fig. 42.6
Fig. 42.5
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