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Osmoregulation = keeping water and salt balanced in the body
• Question 1: why is this important – Come up with three reasons
• Question 2: What water and salt problems do the following organisms face?– Freshwater fish– Marine fish– Marine birds– Marine mammals
• Question 3: How might each group solve those problems?
Definitions• Solute• Solvent• Osmosis• Osmotic Pressure• Osmolarity• Hyperosmotic• Hypoosmotic• Osmoconformer• Osmoregulator
Solutes are dissolved particles in solution (any type)
Water always moves from an area of low osmotic pressure to an area of high osmotic pressure
osmotic pressure:
Osmosis:
Freshwater teleosts: Osmoregulators
Problems?
Solutions?
Hyperosmotic to environment
• Active transport of Na+ into animal
2 K+
3 Na+
ATP
Active transport of salts via skin:
Cl-Cl-
Cl-
• Cl- follows passively (electric gradient)
Cl-
Na+
Marine Strategies
Cartilaginous fish
Marine teleosts:Osmoregulators(hyposmotic to environment)
Problems?
Solutions?
How do they get rid of huge salt load?
Marine reptiles and birds…
seawater
Salt glands!
Nasal fluid urine
Salt glands
• salt is excreted from the gland to outside the body• more concentrated than sea water!
• mechanism is same in marine reptiles-but salt gland is in different
places
Na+ mOsm
seawater 470
sea snake 620
sea turtle 690
Marine Iguana 1000-1400
gull 600-900
cormorant 500-600
petrel 900-1100
How do mammals make concentrated urine?
Each nephron has a loop of Henle:
nephron loopofHenle
Cortex
OuterMedulla
InnerMedulla
Loop of Henle
mammalian nephron:
Na+Na+
Na+Na+
Na+Na+
mOsm
Marine Mammals
1. Long loop of henle in the kidney--concentrated urine--less water lost with waste
2. Diet--carnivores, eating mostly
vertebrates--vertebrates have lower osmolarity
3. Absence of sweat glands
Several Adaptations:
Nitrogenous Wastes affect Water Balance
Proteins Nucleic acids
Nitrogenous waste products
UREAAMMONIA URIC ACID
Excretion
• ammonia
• urea
• uric acid
Teleost fish
chondrichthyes
Birds and reptiles
mammals
Amphibians reptiles
% of urinary nitrogen
Species Habitat Ammonia Urea Uric Acid
Red-eared slider Freshwater
Forest hinge-back tortoise
Moist Terrestrial
Mediterranean spur-thighed tortoise
Dry terrestrial
Texas tortoise Desert
Tortoises and Turtles:
Teleost fish Amphibians
Amphibians
reptiles
Terrestrial summary• Water in:
– Food and drink– Metabolic water
• Water out:– excretion– Evaporative water loss
• Adaptations in the desert?– Extended loop of henle– Reduced evaporative water loss
• (gain in camel nose)– High dehydration tolerance
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