1. 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?

2. Definitions Solute Solvent Osmosis Osmotic Pressure Osmolarity Hyperosmotic Hypoosmotic Osmoconformer Osmoregulator

3. Solutes are dissolved particles in solution (any type) Osmotic pressure: the pressure of water to enter, given the solute concentration --depends on the number of solutes/unit volume (rather than chemical nature of solutes)

4. isosmotic Osmotic pressure: the pressure of water to enter, given the solute concentration (osmotic pressure is equal)

5. hypersmotic (higher osmotic pressure) hyposmotic (lower osmotic pressure) Osmotic pressure: the pressure of water to enter, given the solute concentration

6. Water always moves from an area of low osmotic pressure to an area of high osmotic pressure Hyposmotic (lower osmotic pressure) Hyperosmotic (higher osmotic pressure) osmotic pressure: the pressure of water to enter, given the solute concentration Osmosis: movement of water from an Area with lower osmotic pressure to Higher osmotic pressure

7. Osmolarity = concentration of solutes in a solution Osmolarity vs. Molarity: 150 mMol sucrose= 150 mOsm sucrose 150 mMol NaCl= 300 mOsm NaCl Osmotic pressures are generally described in osmolar units:

8. Definitions Solute: Solvent: Osmosis: Osmotic Pressure: Osmolarity: Hyperosmotic: Hypoosmotic: Osmoconformer: Osmoregulator: Dissolved particles in a solution movement of water from an area with lower osmotic pressure to higher osmotic pressure the pressure of water to enter, given the solute concentration Concentration of solutes in a solution Higher osmotic pressure Lower osmotic pressure What the particles are dissolved in Body fluid isoosmotic with envir. Body fluid osmolarity regulated in opposition to environment

9. Freshwater teleosts: Osmoregulators Problems? water gain salt loss Solutions? move salt into blood Lots of dilute urine * The gills have specialized cells: CHLORIDE CELLS: they result in the active uptake of ions across the gills Hyperosmotic to environment

10. Main osmoregulatory organ = skin Problems? Gaining water Solutions? Losing salt dilute urine pump salt into body Amphibians: osmoregulators Hyperosmotic to environment …but no gills, so no chloride cells…

11. Active transport of Na+ into animal 2 K+ 3 Na+ ATP Active transport of salts via skin: Cl- Cl- follows passively (electric gradient)

12. Cl- Na+ osmoconformers osmoregulator ionoconformer ionoregulator Marine Strategies Cartilaginous fish

13. Marine teleosts: Osmoregulators (hyposmotic to environment) Problems? water loss Solutions? How? excrete salt … salt gain produce little urine (isosmotic to plasma) gain water (food, drink) Chloride Cells in the gills! Actively pump ions OUT

14. Marine reptiles and birds… Osmoregulators Blood is hyposmotic to seawater Can ’ t concentrate urineCan concentrate urine (a *little* bit!)

15. How do they get rid of huge salt load? Marine reptiles and birds… seawater 3% salt Salt glands! Nasal fluid 5 % salt urine 0.3% salt

16. 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 seawater470 sea snake620 sea turtle690 Marine Iguana1000-1400 gull600-900 cormorant500-600 petrel900-1100

17. Marine Mammals Live in seawater…but no chloride cells, no salt glands…? The Mammalian Kidney

18. How does the kidney work? urine isotonic or hypotonic relative to plasma

19. How does the kidney work? Urine is hyperosmotic to plasma

20. The Vertebrate Kidney…

21. How do mammals make concentrated urine? Each nephron has a loop of Henle: nephron loop of Henle

22. Cortex Outer Medulla Inner Medulla Loop of Henle mammalian nephron: Na+ Na+ is pumped out of the filtrate Results in osmotic gradient in the kidney ECF Why does this matter? 300 600 900 300 mOsm 600 900 1200 mOsm 1200

23. Cortex Outer Medulla Inner Medulla Loop of Henle As filtrate passes through the collecting duct, it loses water to the ECF H2OH2O H2OH2O H2OH2O H2OH2O 300 600 900 300 600 900 1200 mOsm 1200 mOsm How concentrated can the filtrate become in this organism? ~150 As concentrated as the ECF

24. Final urine is hyperosmotic to plasma up to 4X in regular terrestrial mammals up to 6X in marine mammals up to 30X in desert mammals!

25. Marine Mammals Live in seawater…but no chloride cells, no salt glands…? 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:

26. Osmoregulation = aquatic animals Question 1: why is this important –Low solute concentration: cells shrink –High solute concentration: cells burst –Cells need proper ion balance to function Muscle, nerve cells; Na+/K+ pump Question 2: Problems? Question 3: solutions? –Problem: solution –Freshwater fish Water gain: produce lots of dilute urine Salt loss: pump salt in through chloride cells in gills –Marine fish Osmoconformers: no regulation ionoconformers: increase plasma solutes—Urea Osmoregulators –Lose water: drink lots of sea water, produce little urine –Gain salt: Chloride Cells in gills –Marine birds Gain salt: excrete salt in salt glands –Marine mammals Gain salt: excrete hi solute urine

27. TERRESTRIAL VERTEBRATES Water Gain: 1.Food/water intake 2.Metabolic water Water Loss: 1.Excretion a)Fecal b)Urinary 2.Evaporative Water Loss a)Cutaneous b)Respiratory 3.Reproduction In humans: + 2.2 L/day + 0.3 L/day - 1.6 L/day - 0.9 L/day Total Water gain and loss: 2.2 + 0.3 = 1.6 + 0.9

28. Water soluble Very toxic Excreted w/lots of water Not water soluble Low toxicity Excreted w/little water Water soluble Low toxicity Excreted w/less water Nitrogenous Wastes affect Water Balance ProteinsNucleic acids Nitrogenous waste products UREAAMMONIA URIC ACID

29. Excretion ammonia urea uric acid Teleost fish chondrichthyes Birds and reptiles mammals Amphibiansreptiles % of urinary nitrogen SpeciesHabitatAmmoniaUreaUric Acid Red-eared sliderFreshwater79174 Forest hinge-back tortoise Moist Terrestrial6614 Mediterranean spur- thighed tortoise Dry terrestrial42252 Texas tortoiseDesert4393 Tortoises and Turtles: Teleost fishAmphibians reptiles

30. Mammals: most drink, eat foods high in water very concentrated urine BUT, what about desert mammals?

31. How do Kangaroo Rats Cope? don’t pant few sweat glands LONG loop of henle Human urine= 1200 mOsm Kangaroo rat = 5500 mOsm eat dry food * don’t drink! don’t tolerate dehydration! C 6 H 12 O 6 + 6O 2 6 CO 2 + 6H 2 O Metabolic water: How? 1 g glucose0.6 g water

32. 100g barley35 g Water gains:Water losses: 54 mL: oxidation water 6 mL: absorbed water 16.1 mL: urine, feces 43.9 mL: evaporation 60 mL water = = Urine = 9x higher osmolarity than sea water!!

33. 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