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Osmotic and Ionic Regulation

Osmotic and Ionic Regulation. All animals face osmotic and ionic stresses. Stresses depend on environment: Aquatic Marine Freshwater Brackish (estuarine) Terrestrial. Regardless of their environment, all animals must be capable of maintaining isosmoticity between

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Osmotic and Ionic Regulation

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  1. Osmotic and Ionic Regulation All animals face osmotic and ionic stresses. • Stresses depend on environment: • Aquatic • Marine • Freshwater • Brackish (estuarine) • Terrestrial

  2. Regardless of their environment, all animals must be capable of maintaining isosmoticity between the ICF (intracellular fluid) and ECF (extracellular fluid). Regulating ICF osmotic conc. in response to changes in the osmotic conc. of the ECF is called: Cell Volume Regulation

  3. HYPERTONIC HYPOTONIC

  4. Unchecked swelling under hypotonic conditions can lead to OSMOTIC LYSIS

  5. Regulatory Volume Decrease (RVD) If the osmotic conc. of the ECF decreases, water moves into the ICF and the cell swells. H2O

  6. Regulatory Volume Increase (RVI) If the osmotic conc. of the ECF increases, water moves out of the ICF and the cell shrinks. H2O

  7. Na+ H+ H2O + CO2 Cl- HCO3- H2O RVI - Ionic Fluxes osmotically shrunken cell

  8. H+ K+ H2O + CO2 HCO3- Cl- H2O RVD - Ionic Fluxes osmotically swollen cell

  9. F.A.A. = free amino acids H2O F.A.A. SW FW F.A.A. ICF content H2O 0 15 Days FW SW ICF content

  10. Animals can reduce the amount of volume regulation their cells must do by regulating ECF osmotic concentrations. Osmotic and ionic regulation occurs in both aquatic and terrestrial spp. We’ll look at aquatic organisms first

  11. isosmotic line osmoregulator osmoconformer 1000 ECF osmolarity (mOsm) 1000 0 Medium osmolarity (mOsm) Stenohaline - able to tolerate a narrow salinity range Euryhaline - able to tolerate a wide salinity range

  12. Volume changes on transfer to dilute seawater

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