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Lecture Exam Monday. 100 point exam covers lectures, assigned readings 8-12 short answer questions; 4-6 pts ea complete, concise answer ex: definition; short description 3-5 longer questions; 10-15 pts ea Finish by 2:55--budget time Power Point lectures on blackboard
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Lecture Exam Monday • 100 point exam • covers lectures, assigned readings • 8-12 short answer questions; 4-6 pts ea • complete, concise answer • ex: definition; short description • 3-5 longer questions; 10-15 pts ea • Finish by 2:55--budget time • Power Point lectures on blackboard • Chapters:1, 2, 12, 13, 3, 14, 4, 15, 5 end
4. Swim bladder • low density • adjustable • most bony fishes • lost secondarily in some species end
Two types of swim bladders: • Physostomous • pneumatic duct • soft-rayed teleosts--herrings, salmonids, catfishes, cyprinids, eels, etc. • Physoclistous • blood/circulatory system • spiney-rayed teleosts--Acanthopterygii, sunfishes, perch, most marine fishes end
Effects of depth on swim bladder volume • pressure increases 1 ATM/10m • swim bladder must be adjustable • Physostomous fishes adjust volume by gulping or spitting air. • mostly shallow water species • gas-spitting reflex • gulp air at surface end
Physoclistous inflation/deflation • circulatory system--source of gases • rete mirabile (wonderful net) --inflation • oval window--deflation • Problem: fish need greater pressure in swim bladder than is achieved by equilibrium with blood gases end
O2 O2 O2 gills rete Oxygen equilibrium—swim bladder inflation hemoglobin How are high pressures achieved? DO plasma gaseous O2 water swim bladder blood end
lactic acid Bohr & Root afferent blood efferent blood Counter-current multiplication system Diagram of basic functional unit of rete (inflation) O2heme pO2 O2heme 1 pO2 pO2 swim bladder O2heme pO2 end
Function of Rete Mirabile 1. Hemoglobin saturated with O2 (O2heme) plasma O2 low (p O2) end
lactic acid afferent blood efferent blood Counter-current multiplication system O2heme pO2 O2heme 1 2 pO2 pO2 swim bladder O2heme pO2 end
Function of Rete Mirabile 2. Lactic Acid Secretions heme dumps O2to plasma pO2diffuses into swim bladder to equil. end
lactic acid afferent blood efferent blood Counter-current multiplication system O2heme pO2 O2heme 1 2 pO2 pO2 swim bladder O2heme pO2 3 end
Function of Rete Mirabile 3. Multiplying effect: pO2 diffuses from efferent capillary to afferent cap. Longer capillaries yield more efficient exchange of oxygen, higher pressures end
Summary of what happens to O2 • Steady supply of oxygen in • Little or none leaves • PO2 accum. in plasma • Diffusion into SB O2 O2 end
Physoclistous swim bladder • Pressures up to 300 ATM in some deep sea fishes • Gases mostly O2, some CO2 and N2 • Guanine crystals in SB wall reduce permeability • Deflation occurs at oval window • dense bed of capillaries on SB wall • gasses diffuse into blood • mucus layer covers window during inflation end
Summary: • Diffusion of O2; controlled by structure & function • Relationship O2 bound to hemoglobin versus O2 in plasma • Effect of pH on affinity/capacity of hemoglobin for O2 (Bohr & Root) • Counter-current multiplier • length of capillaries • counter-current flow of blood end
Thermoregulation: • Cold-blooded -poor descriptor • Poikilotherm (n); poikilothermic (adj) • variable body temperature • opposite = homeotherm • Ectotherm (n); ectothermic (adj) • temp. determined by environment • opposite = endotherm end
Heat generated by metabolism skin body gills skin Why are fishes ectothermic? end
Behavioral Thermoregulation • nearly all fishes • choose from available temperatures • concept of temperature preference end
Temperature Preference: 40 final preferendum 10 10 40 bluegill Preferred temperature C guppy chum salmon Acclimation temperature C end
Physiological Thermoregulation • few fishes--tunas & lamnid sharks • fish are active --generate heat • rete mirabile for heat exchange & conserv. • fish are large--low surface area to mass ratio • body surf. area increases as square of length • body mass increases as cube of length end
rete mirabile heat Physiological Thermoregulation skin gills body skin
Counter-current blood flow from body high heat venous blood Temperature arterial blood from gills low Distance along capillaries (rete) end
Counter Current flow: • fluid flowing in opposite directions • exchange of heat or gas perpendicular to flow • efficiency versus speed end
heat Hypothetical Co-current blood flow: from body high counter-current venous blood Temperature arterial blood from gills low Distance along capillaries (rete) end
Hypothetical Co-Current flow: • fluid flowing in same direction • exchange of heat or gas perpendicular to flow • speed versus efficiency end