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14 Cards in this Set
- Front
- Back
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Blood and Circulatory System
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Circulatory System: -transports oxygen and nutrients to the cells of the body and removes carbon dioxide and other metabolic wastes. Also carries hormones from site of release to their target tissues |
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Circulatory System: Closed System
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Closed System: -heart pumps blood through gills (branchial capillary bed) and systemic capillary beds via arteries and returns to heart through vein -blood contains hemoglobin, which binds with O2 |
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Circulatory System: Circulatory System
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Specialized circulations -lungfishes: pulmonary circuit -also special circulations in other air-breathing fishes |
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Buoyancy
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-animal tissues are denser than seawater
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4 strategies for achieving neutral buoyancy
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1. incorporate large quantities of low density compounds in the body 2. generation of lift by fins/body surfaces ring swimming 3. reduction of heavy tissues such as bone and muscle 4. incorporation of gas bladder |
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Buoyancy: Elasmobranchs (sharks and rays)
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-no gas bladder (some sand and tiger sharks observed swallowing air into stomach for buoyancy -contain large quantities of lipids, including squalene, esp in large livers -cartilage skeleton less dense than bone -heterocercal tail and angled body (not pectoral fins) provide lift while swimming (most sharks must keep swimming to prevent sinking) |
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Buoyancy: Elasmobranchs (sharks and rays)
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-some deep-sea sharks found to actually be positively buoyant: must swim to stay down -bluntnose sixgill shark & prickly shark -Very large, oil filled livers -May help sneak up on prey from below |
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Buoyancy
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-some bony fishes use low density oils to increase buoyancy -many bony fishes have a gas bladder for buoyancy control |
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Gas Bladders
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-found in bony fishes -volume can be adjusted to compensate for depth, temperature, salinity -occupies about 5% of body volume in seawater fishes (fish about 5% denser than seawater) -or about 7% in freshwater fishes (fish 7% denser than freshwater) |
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Gas Bladders: Physostomous
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-has connection to gut through pneumatic duct -found in the more ancestral bony fishes (soft-rayed teleosts) -filled by gulping air at surface -limits fish to shallow water (can't increase volume at depth to counter-act greater pressure (1 atm pressure added for every 10 meters of depth) -some have gas gland to aid filling |
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Gas Bladders: Physoclistous
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-closed (no connection to gut cavity) -found in more derived teleosts (spiny fin fishes) -has gas gland |
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Gas Bladders: Physoclistous(Gas Gland)
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-Acidifies blood to cause release of oxygen (and some other gasses) -source of gas inflation - associated with vascular structure called a rete mirabilia , or "wonderful net" - counter current system of blood vessels to and away from gas gland - concentrates gasses -allows generation and maintenance of very high pressures in gas bladder, 300+ atm in some deep-sea fishes -correlation between retial capillary length and habitat depth in fish |
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Gas Bladder
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-guanine crystals in multiple layers in gas bladder wall reduce loss of O2 -Deflation of physoclistous gas bladder accomplished by diffusion of gas back into blood at an area termed the Oval (patch of densely packed capillaries, exposed area controlled by muscles) |
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Gas Bladder
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-Maintaining a gas gland for gas bladder inflation is metabolically expensive -Deep-sea pelagic fish (>1000 m) usually have no gas bladder (costly to maintain, have reduced skeletons and muscle tissue) -Deep-sea bottom fishes may have gas bladders (more energy available at ocean bottom) |
