Excretion Osmoregulation Quiz which of the following two fish will take on water into its body osmotically Freshwater or saltwater Quiz the loop of Henle is a structure inside the mammalian kidney that absorbs water and therefore functions in water retention If an organism wanted to maximally retain water it would make this loop of Henle Make it longer Quiz the excretory system plays an important role in controlling the acidbase balance of the system To do this the kidneys will actively control what types of ions OH HCO3 H both b and c none of the above Important of evolutionary history o Oceans are far more phylogenetically diverse than other biomes larger b c much of life originated there Many species have ancestors from ocean o Many groups have invaded freshwater land and subsequently reinvaded the ocean Water makes up a substantial part of an organism s mass o Accounts for over half of body weight 60 in many animals including us Up to 95 in some animals jellyfish Types of animal fluids o Intracellular fluids cytoplasm o Extracellular fluids Interstitial fluid lies between cells and other tissue components Blood plasma Fluid composition o Fluid provides context for cells organelles and molecular function o Ion concentration plays key roles in Enzyme and protein function pH Electrical gradients and nervous impulses o Water determines Ion concentration Volume of cells and tissues o All animals regulate body fluid composition No known organism is exactly identical osmotically to their environment though some are closer than others Osmotic pressure the pressure applied by a solution that influences the flow of water across a semipermeable membrane via osmosis Osmosis is defined as the transfer of water across a semipermeable membrane from areas of low solute concentration to areas of high solute concentration trying to equalize high solute less water Protonephridia in flatworms o Flame cells ciliated solenocytes flagellated Metanephridia o Annelids arthropods molluscs o Primary urine water taken up is modified into secondary urine through selective reabsorption of ions by cells lining metanephridium funnel to pull in water instead of cilia Kidneys o Regulate the composition of blood plasma by removing water salts and other solutes Urine Plasma U P ratios o Comparison of osmotic pressure in urine and plasma o U P 1 isosmotic urine urine same as blood plasma organism is in its ideal natural environment o U P 1 hyposmotic urine water is excreted solutes are retained denominator is greater species migrated from open ocean to estuary prefers open ocean but is moving to an area of lower solute concentration so it gains water to equalize and then has a lot to release o U P 1 hyperosmotic urine water is retained solutes are excreted environment is too salty so fresh water tries to leave it s body to put more water in the environment Acid Base Balance o Kidneys work in concert with buffering systems blood respiration to keep pH in normal range o Normal metabolism produces an excess of H o Bicarbonate carbon dioxide buffer system in blood can neutralize excess H Water salt regulation osmoregulation o Osmotic regulation maintain constant osmotic pressure in blood plasma by controlling solute concentrations o Osmoregulator vs osmotic conformer What kind of marine organisms would be osmoregulators o Mussels osmoconformer o Green crab osmoregulator and osmoconformer o Shrimp osmoregulator o Constant environment osmoconformer o Variable environment osmoregulator Water salt regulation ionic regulation o Osmotic regulation o Ionic regulation many types of ionic regulation in marine systems b c each can be independently controlled Water salt regulation volume regulation o Control water volume relatively rare o Salt water fish taking on water decrease osmotic pressure decrease ionic concentration increase body fluid volume Ocean salinity o 34 36 g kg 1000 mOsm milliosmoles fairly constant solute concentration o Mainly sodium chloride Quiz osmotically animals can be conformers or regulators Would you expect there to be ionic conformers and volume conformers Ionic possibly but only for certain ions so they re always regulating something volume no Marine invertebrates o Most nearly isosmotic with seawater Molluscs Porifera sponges Cnidarians Annelids Echinoderms Hagfish vertebrate is close to concentrations of invertebrates environment rare Urine formation in decapod crustaceans o Glands resemble large nephrons o Allows crustaceans very accurate control of osmotic balance even under extreme conditions Urine formation in molluscs o Bivalves and cephalopods have 2 kidneys other molluscs have 1 o Use beating of heart to give urine the pressure it needs to push out urine Hagfish is it all in the ancestry o Primitive vertebrates o Resemble invertebrates Isosmotic blood Blood solutes principally Na and Cl Ionic regulation similar to invertebrates o Evolutionary history Jawless vertebrates moved to freshwater and gave rise to all jawed vertebrates Hagfish jawless vertebrates never left the ocean so ancestors are marine invertebrates Water solute balance in freshwater fish o Osmollarity 250 350 mOsm water will go into them and produce lots of urine o Open ocean to freshwater Water solute balance in marine fish o Opposite freshwater to open ocean o 300 to 500 mOsm water will leave their body drink a lot have lots of salt in it incredibly concentrated urine get rid of salt across gills o Less permeable to water than freshwater fish Specific example southern flounder reducing ions costs 8 17 of metabolic costs of fish lots of energy Sharks and other elasmobranchs o Add urea and TMAO to have a higher osmotic pressure than water o Bringing in new water all the time Quiz would you expect osmoregulation to be a bigger problem for a mammal that consume invertebrates or for mammals that consume fish Invertebrates or fish o Eating invertebrates is the same as drinking seawater so invertebrates are a bigger problem Other marine invertebrates birds reptiles mammals o 400 mOsm hyposmotic all descended from terrestrial ancestors o Don t expose gas exchange surfaces to seawater b c are air breathers Birds and reptiles o Salt excreting glands o Location of salt glands discharge o Glands can grow or shrink Mammals o No salt glands o Substantial variation Some drink sea water sea otters manatees others do not dolphins Concentrated urine hyperosmotic in some pinnipeds seals o Whales and dolphins Drink very little water Do take