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Comparative Vertebrate Physiology. Extrarenal mechanisms of osmoregulation. Lecture summary. Fish: gills Amphibians: Integument/urinary bladder Reptiles and birds: Salt gland/lower intestine Mammals: Nasal exchange + kangaroo rat. Marine teleosts. Marine teleosts- chloride cells.
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Comparative Vertebrate Physiology Extrarenal mechanisms of osmoregulation
Lecture summary • Fish: gills • Amphibians: Integument/urinary bladder • Reptiles and birds: Salt gland/lower intestine • Mammals: Nasal exchange + kangaroo rat
Marine teleosts- chloride cells • Operation • Na/K pump • Na/Cl/K cotransporter • Na and Cl transported into seawater Chloride cell(note mitochondria)
Freshwater teleosts • Pavement cells pump Na+ into blood Pavement cell Chloride cell
Amphibians • Permeable integument • High rates of respiration and EWL • Desert adapted frogs
Amphibians • Permeable urinary bladder • Recycling water-urine is more concentrated
Reptiles • Salt gland location • Supraorbital • Lingual • NaCl or KCl Salt secretion droplets
Reptiles & birds-salt gland Salt gland cells
Salt gland • Function (same as chloride cell) • Na/K pump • Na/Cl/K cotransporter • Na and Cl transported into environment
Reptiles: Lower Intestine • Cloaca • Urinary bladder in reptiles only • Purpose: Na+, K+, Cl-, water absorption
Birds: Lower intestine • Cloaca (temporary storage organ) • No urinary bladder • Purpose: Na+, K+, Cl-, water absorption
Mammals • Strategies • Keep mouth closed • Nasal countercurrent exchange
Mammals • Desert adaptations
Reptile water budget • Intake: drinking 25%, food 52%, metabolic 23% • Outlet: feces/urine 36%, evaporation 58%, salt gland 6%
Bird water budget • Intake: drinking 93%, food 2%, metabolic 5% • Outlet: feces/urine 64%, evaporation 36%, salt gland ?? (data from ostrich - no salt gland)
Mammals • Intake: drinking 69%, food 4%, metabolic 26% • Outlet: feces 7%, urine 50%, evaporation 43%