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 acid-base 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 historyo Oceans are far more phylogenetically diverse than other biomes (larger b/c much of life originated there) Many species have ancestors from oceano Many groups have invaded freshwater/land, and subsequently reinvaded the ocean- Water makes up a substantial part of an organism’s masso Accounts for over half of body weight 60% in many animals (including us) Up to 95% in some animals (jellyfish)- Types of animal fluidso Intracellular fluids (cytoplasm)o Extracellular fluids Interstitial fluid lies between cells and other tissue components Blood plasma- Fluid compositiono Fluid provides context for cells, organelles, and molecular functiono Ion concentration plays key roles in Enzyme and protein function pH Electrical gradients and nervous impulseso Water determines Ion concentration Volume of cells and tissueso 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 flatwormso Flame cells (ciliated), solenocytes (flagellated)- Metanephridiao Annelids, arthropods, molluscso 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)- Kidneyso Regulate the composition of blood plasma by removing water, salts, and other solutes- Urine/Plasma (U/P) ratioso Comparison of osmotic pressure in urine and plasmao U/P=1 isosmotic urine, urine same as blood plasma, organism is in its ideal natural environmento 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 releaseo 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 Balanceo Kidneys work in concert with buffering systems (blood/respiration) to keep pH in normal rangeo Normal metabolism produces an excess of H+o Bicarbonate-carbon dioxide buffer system in blood can neutralize excess H+- Water/salt regulation: osmoregulationo Osmotic regulation: maintain constant osmotic pressure in blood plasma by controlling solute concentrationso Osmoregulator vs. osmotic conformer - What kind of marine organisms would be osmoregulators?o Mussels—osmoconformero Green crab—osmoregulator and osmoconformero Shrimp—osmoregulator o Constant environment=osmoconformero Variable environment=osmoregulator - Water/salt regulation: ionic regulationo Osmotic regulationo Ionic regulation: many types of ionic regulation in marine systems b/ceach can be independently controlled- Water/salt regulation: volume regulationo Control water volume, relatively rareo Salt water fish taking on water (decrease osmotic pressure, decrease ionic concentration, increase body fluid volume)- Ocean salinityo 34-36 g/kg 1000 mOsm (milliosmoles) fairly constant solute concentrationo 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 invertebrateso 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 crustaceanso Glands resemble large nephronso Allows crustaceans very accurate control of osmotic balance even under extreme conditions- Urine formation in molluscso Bivalves and cephalopods have 2 kidneys, other molluscs have 1o Use beating of heart to give urine the pressure it needs to push out urine- Hagfish—is it all in the ancestryo Primitive vertebrateso Resemble invertebrates Isosmotic blood Blood solutes principally Na+ and Cl- Ionic regulation similar to invertebrateso 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 fisho Osmollarity (250-350 mOsm), water will go into them and produce lots of urineo Open ocean to freshwater- Water-solute balance in marine fisho Opposite—freshwater to open oceano 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 gillso 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 watero 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 invertebratesare a bigger problem - Other marine invertebrates (birds, reptiles, mammals)o 400 mOsm hyposmotic—all descended from terrestrial ancestorso Don’t expose gas exchange surfaces to seawater b/c are air breathers- Birds and reptileso Salt excreting glandso Location of