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; 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

Oxygen equilibrium—swim bladder inflation DO hemoglobin plasma gaseous O 2 O2O2 O2O2 O2O2 gills blood rete water swim bladder How are high pressures achieved? end

Counter-current multiplication system afferent blood efferent blood O 2 heme  pO2pO2 O 2 heme   p O 2 pO2pO2 swim bladder O 2 heme   pO 2  lactic acid Bohr & Root 1 Diagram of basic functional unit of rete (inflation) end

Function of Rete Mirabile 1. Hemoglobin saturated with O 2 (O 2 heme) plasma O 2 low (p O 2 ) end

Counter-current multiplication system afferent blood efferent blood O 2 heme  pO2pO2 O 2 heme   pO 2 pO2pO2 swim bladder O 2 heme   pO 2  12 lactic acid end

Function of Rete Mirabile 2. Lactic Acid Secretions heme dumps O 2 to plasma pO 2 diffuses into swim bladder to equil. end

Counter-current multiplication system afferent blood efferent blood O 2 heme  pO2pO2 O 2 heme   pO 2 pO2pO2 swim bladder O 2 heme   pO 2  lactic acid 12 3 end

Function of Rete Mirabile 3. Multiplying effect: pO 2 diffuses from efferent capillary to afferent cap. Longer capillaries yield more efficient exchange of oxygen, higher pressures end

O2O2 O2O2 1.Steady supply of oxygen in 2.Little or none leaves 3.PO 2 accum. in plasma 4.Diffusion into SB Summary of what happens to O 2 end

Physoclistous swim bladder Pressures up to 300 ATM in some deep sea fishes Gases mostly O 2, some CO 2 and N 2 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 O 2 ; controlled by structure & function Relationship O 2 bound to hemoglobin versus O 2 in plasma Effect of pH on affinity/capacity of hemoglobin for O 2 (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

Why are fishes ectothermic? Heat generated by metabolism skin body gills end

Behavioral Thermoregulation nearly all fishes choose from available temperatures concept of temperature preference end

Temperature Preference: Acclimation temperature C Preferred temperature C bluegill chum salmon guppy final preferendum 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

Physiological Thermoregulation body skin gills heat rete mirabile

Counter-current blood flow Distance along capillaries (rete) Temperature low high arterial blood venous blood heat from gills from body end

Counter Current flow: fluid flowing in opposite directions exchange of heat or gas perpendicular to flow efficiency versus speed end

Distance along capillaries (rete) Temperature low high Hypothetical Co-current blood flow: from gills from body arterial blood venous blood counter-current heat end

Hypothetical Co-Current flow: fluid flowing in same direction exchange of heat or gas perpendicular to flow speed versus efficiency end