Post on 01-Jan-2016
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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 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
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%