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Lecture 9

Lecture 9 - Osmoregulation completed.pdf

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University of Toronto St. George
Chris Garside

Lecture 9 OsmoregulationNovember 22 20131247 AM BIO270 Page 1 Its always going to be using transportersinserting transporters in specific locations in cells to move ions so that water can flow osmoticallyIn any case we find that its like thatOsmoconformers vs osmoregulators be comfortable with these 2 termsOsmoregulator1This doesnt mean that the composition of the ions solutes on the inside is the same on the outside2It means the overall concentration is the same 3This becomes important if you live in a marine environment NaK how many physiological processes those can effectSo marine organisms keep na and K pretty low and use some other 4solute to build up that osmotic concentration so its the same as sea waterbut you dont have movement of water so you dont have the effect of very high concs of na and or K whatever it happens to be inside the cell5Not necessariliy an ionic regulator dont need to go into detail here 6Regulators vs conformersweve talked about this beforeOsmolarity Ability of solutions to induce water cross across Water vssolute need to be confident with this water is simply going membranesto follow we cannot actively transport water in all casesOsmoles number of moles of a unit that contributes to osmotic There are transporters like aquaporins but those just facilitate the pressuremovement of water not active transport Water following the movement of ionsWherever you live you have challengesFreshwater has to be osmoregulators weve talked about this how lower concs of ions and solutes are in freshwaterCells dont just function at those levels so there must be a way to bring those ions into the body and stop the water from moving inEuryhaline orgs are able to adapt to a wide range of salinities or else Classificationthey die they are good regulators OfAnimalsStenohaline orgs can only manage a narrow range of fluctuation in Depending salinityosmotic concOnIn fresh water you must be an osmotic conformer you must find a way TheirAbility toto stop all that water from moving into the body of cells changing the Tolerate changesosmotic concentrationIn externalMarineosmolarityInvertebrates tend to be osmoconformershowever most 1vertebrates are osmoregulaters2In marine the osmotic conc is very high salts coming in and you have to find a way to regulate it and these orgs have specialized glandsTerrestrial3Key thing here is loss of water and again many orgs have many adaptationsthey stop the movement of water and dehydration so then animals tend to lose water in the terrestrial environment BIO270 Page 2
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