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Osmoregulation = keeping water and salt balanced in the body

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

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Osmoregulation = keeping water and salt balanced in the body

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

  5. hypersmotic hyposmotic (higher osmotic pressure) (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 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 Hyperosmotic (higher osmotic pressure) Hyposmotic (lower osmotic pressure)

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

  8. Definitions Dissolved particles in a solution • Solute: • Solvent: • Osmosis: • Osmotic Pressure: • Osmolarity: • Hyperosmotic: • Hypoosmotic: • Osmoconformer: • Osmoregulator: What the particles are dissolved in 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 Body fluid isoosmotic with envir. Body fluid osmolarity regulated in opposition to environment

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

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

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

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

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

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

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

  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

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

  23. ~150 H2O H2O H2O As concentrated as the ECF H2O 1200 mOsm 1200 mOsm As filtrate passes through the collecting duct, it loses water to the ECF Loop of Henle How concentrated can the filtrate become in this organism? 300 300 Cortex Outer Medulla 600 600 900 900 Inner Medulla

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

  25. Marine Mammals Several Adaptations: 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

  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 Total Water gain and loss: 2.2 + 0.3 = 1.6 + 0.9 In humans: • Water Loss: • Excretion • Fecal • Urinary • Evaporative Water Loss • Cutaneous • Respiratory • Reproduction • Water Gain: • Food/water intake • Metabolic water + 2.2 L/day - 1.6 L/day + 0.3 L/day - 0.9 L/day

  28. Proteins Nucleic acids Nitrogenous waste products AMMONIA UREA URIC ACID Nitrogenous Wastes affect Water Balance • Water soluble • Very toxic • Excreted w/lots of water • Water soluble • Low toxicity • Excreted w/less water • Not water soluble • Low toxicity • Excreted w/little water

  29. Excretion Tortoises and Turtles: • ammonia • urea • uric acid Teleost fish Amphibians reptiles chondrichthyes Teleost fish Amphibians reptiles mammals Amphibians Birds and reptiles

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

  31. C6H12O6 + 6O2 6 CO2 + 6H2O 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! How? Metabolic water: 1 g glucose 0.6 g water

  32. 100g barley Water gains: = Water losses: = 35 g 54 mL: oxidation water 6 mL: absorbed water 16.1 mL: urine, feces 43.9 mL: evaporation 60 mL water 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

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