1 / 24

Osmoregulatory Systems in Fishes

Osmoregulatory Systems in Fishes. Maintaining homeostasis with respect to solute concentrations and water content. OSMOREGULASI

emiliac
Télécharger la présentation

Osmoregulatory Systems in Fishes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Osmoregulatory Systems in Fishes Maintaining homeostasis with respect to solute concentrations and water content

  2. OSMOREGULASI • SistemOsmoregulasi / regulatorosmotik/osmoregulatorialahsistempengaturankeseimbangantekananosmotikcairantubuh (air dandarah) dengantekananosmotik habitat(perairan). • Pengaturantekananosmotikcairantubuh yang layakbagikehidupanikan, sehinggaproses-prosesfisiologistubuhnyaberfungsi normal.

  3. Definitions • Homeostasis = maintaining steady state equilibrium in the internal environment of an organisms • Solute homeostasis = maintaining equilibrium with respect to solute (ionic and neutral solutes) concentrations (i.e. salts) • Water homeostasis = maintaining equilibrium with respect to the amount of water retained in the body fluids and tissues

  4. Osmoregulation in different environments • Each species has a range of environmental osmotic conditions in which it can function: • stenohaline - tolerate a narrow range of salinities in external environment • euryhaline - tolerate a wide range of salinities in external environment • short term changes: estuarine - 10 - 32 ppt, intertidal - 25 - 40 • long term changes: diadromous fishes (salmon)

  5. Four osmoregulatory strategies in fishes • Isotonic atau isoosmotik : jika tubuh hewan mempunyai tekanan osmotik cairan = tekanan osmotik lingkungan (Hagfish) • Hipoosmotik : jika tekanan osmotik cairan tubuh relatif konstan lebih rendah daripada lingkungannya (Ikan air laut) • Hiperosmotik : jika tekanan osmotik cairan tubuh relatif konstan tinggi daripada lingkungannya (Ikan air tawar)

  6. Osmoregulation in marine and freshwater fish

  7. Marine fish face two problems: they tend to lose water and gain ions.

  8. Freshwater fish face two problems: they tend to lose ions and gain water.

  9. Salmon

  10. Osmoconforming (no strategy) Hagfish internal salt concentration = seawater. However, since they live in the ocean....no regulation required! Komposisigaramdalamdarah hagfish menyerupai air lautsehingga hagfish tidakmelakukanosmoregulasisehinggadisebutisotonis

  11. For the most part, marine invertebrates are in osmotic equilibrium with the seawater. That is, their salty internal fluids hold as much salts as does the surrounding aquatic medium. Stated another way, the principal ions that are found in the fluids that bathe the cells of the body are the same, and occur in approximately the same concentrations, as those found in seawater. There is no problem of water balance—the rate of diffusion of water into the body is the same as the rate at which water diffuses out. Under conditions such as this, we say the animals exist in an isotonic environment (iso means “the same”).

  12. Elasmobranchs (sharks, skates, rays, chimeras) • Maintain internal salt concentration ~ 1/3 seawater, make up the rest of internal salts by retaining high concentrations of urea & trimethylamine oxide (TMAO). • Bottom line…total internal osmotic concentration equal to seawater! • How is urea retained? • Gill membrane has low permeability to urea so it is retained within the fish. Because internal inorganic and organic salt concentrations mimic that of their environment, passive water influx or efflux is minimized.

  13. ELASMOBRANCH FISHES Marine elasmobranchs have solved the problem of osmoregulation in an entirely different way. They have evolved a specialized segment of the nephron that reabsorbs urea and returns it to the blood. Osmoregulation in a marine shark. The concentration of solutes in the body fluids is greater than in the outside medium. Open arrows indicate movement of substances by passive diffusion, closed arrows indicate movement of substances by active transport mechanisms

  14. What about rapid ion flux? Euryhaline • Short-term fluctuations in osmotic state of environment, e.g. in intertidal zone or in estuaries where salinity can range from 10 to 34 ppt with the daily tidal cycle: • these fish have both kinds of chloride cells • when salinity is low, operate more like FW fishes • when salinity is high, operate like marine fishes • kidneys function only under low salinity conditions

  15. Euryhaline • Diadromy takes two general forms: • Anadromy: Adults spawn in freshwater; juveniles move to saltwater for several years of feeding and growth, and then migrate back to freshwater to spawn. • Chinook Salmon (Oncorhynchustshawytscha

  16. 2. Catadromy: Adults spawn at sea; juveniles migrate to freshwater for several years to feed and then return to the sea to spawn American eel (Anguilla rostrata)

  17. What about stress?? • Stressors (handling, sustained exercise such as escape from predator pursuit) cause release of adrenaline (epinephrine) - for mediating escape, etc. • Adrenaline causes diffusivity of gill epithelium to increase, i.e. “leaky cell membranes” water & ions) • This accentuates the normal osmoregulatory challenge for FW or marine fishes

  18. Osmoregulatory organ • Insang 2. Ginjal • Usus • Merangkummateritgl 15 (pengertiandifusi, osmosis, osmoregulasi air laut&airtawar, osmoregulasielasmobranch) *silahkandicarifungsidari organ osmoregulasidiatasdandikumpulkanharijumatjam 11.30-12.30 diged. D lantai 1

More Related