uh tonicity of solutions now actually we've already talked about hypotonic isotonic and hypertonic we covered it back in section uh B and we even had a couple of questions on the test if you expose cells to a hypotonic solution they swell if you expose them to a hypertonic they shrivel up they collapse they implode that's called crenation so we've already dealt with it what we're going to do now is we're going to learn how to quantify numerically quantitatively Express the relative tonicity so I begin by reminding you that diffusion of water across cell membranes is called osmosis or osmotic flow technically water is simply flowing from an area of higher water concentration to an area of lower water concentration sometimes people like to think of it as in the re inverse way uh in a sense you can think of Osmosis is water being drawn towards the area where there's a higher total solute concentration because wherever there's more solute there's less water all right water's just going from an area where there's more water to an area where there's less water if there's less water there's more solute either way it's the same thing the total solute concentration in a fluid is called its ton that's important the total amount of of uh solutes uh in a any fluid is called its tonicity the tonicity or total solute concentration of body fluids is very critical if the extracellular fluids like blood became hypertonic which it means a higher solute concentration than normal water would be drawn out of the cells and the result is crenation but if the extracellular fluids become hypotonic a lower solute concentration than normal water will be drawn into the cells as it were and the result is swelling of the cells and even uh Li let's look on the next page and the next page actually shows drawings and actual photo micrographs of red blood cells so in the top picture it shows a red blood cell so surrounded by what's called an isotonic fluid that means it has the same proportion of solute and water outside the cell as inside the cell so since the concentration of water is the same outside is inside ISO meaning the same so this is a happy cell and here's an actual photograph of red blood cell smiling okay now on the other hand if we place cells including red blood cells in a hypotonic fluid a fluid that is proportionately lower in solute and higher in water hypo atonic means low in low concentration of solute and high in water then uh water will flow into the cell causing the cells to swell and eventually burst here's an actual photograph of red blood cells look at how they don't look happy look at them they're about ready to burst we don't want that and then the third possibility is surrounding uh the cells with a hyperonic solution where it's high in solute and low in water so water overall there's a net flow of water out of the cell to the outside of the C cell where there's less water and more solute hypertonic high in solute and as the water flows out of the cell the cell starts to implode uh and here's look at this these guys do not look happy right these red blood cells are about ready to collapse so this is a very important subject now back on page nine we wrote that clinically clinically it would be useful to identify whether a patient perhaps a patient with kidney disease perhaps a patient with kidney failure suffered from hypertonia or hypotonia you say how what do you mean if somebody's kidneys don't work aren't the kidneys supposed to excrete the excess water or excess salt that we ingest or swallow if somebody's kidneys don't work and you're drinking water or eating salty foods then you're changing the tonis of your body fluids and the organ that normally gets rid of the excess water gets rid of the excess salt isn't working so therefore your body fluids are going to start to become hypo or hypertonic if we knew how to quantify this how to express quantitatively how hypotonic or how how hypertonic if they were hypertonic you could give them just fluids hypotonic fluids to compensate if they were hypotonic you could give them solutes such as salt the problem is how do we express the total uh quantity of soles how do we quantify the tonicity so that we know how much fluid or how much salt to give them now you your first thought is well so nobody knows how to do that so we don't know how to but we do know how to do it and that's exactly what is done everything is done quantitatively that's what all this testing is done in the hospital now the uh the the unit that we use to quantify the tonicity is a unit called Osmos and uh it's called Osmos it is the contraction of two words osmosis and mole so it's combining the concept of Amo and osmosis the movement of water now this concept this term is only used in physiology and in medicine you never learn it in a chemistry class or bioch chemistry for that matter you could have had four years of chemistry and never learned this unit why because in a chemistry class you just put chemicals in a test tube it has nothing to do with cells and cells bursting or collapsing because the solution is is hypo or hypertonic so they don't deal with cells they just deal with chemicals only living cells May swell up with water or collapse because of not enough water so it only becomes important in terms of physiology of cells and uh in medicine now uh the uh in terms of uh the number of Osmos per liter that's called osmolarity but more commonly we talk about milliosmoles per liter which we call millios molarity let me introduce the concept to you and then we'll take a break and then after the break I'm going to go just a little bit further I want to finish this handout and then we'll switch to lecture topics but let me introduce the concept to you many years ago and I was trying to figure out as a much younger teacher uh how do I convey this concept of an osmo or a miloso to my students and uh I actually HIIT upon something uh and here's how I'm going to explain it if you uh if you uh went to uh if you uh took your early uh grades of school if you were went to school in the United States and you had second and third grade in the United United States you heard from your arithmetic teacher the following expression you can't add apples to oranges anybody ever hear that term it's a classic expression you cannot add apples to oranges so if Johnny has three apples right and Billy has two oranges what do they have together three apples and two oranges because you can't add apples and oranges they're two different things that's what your arithmetic teacher teaching all right common I know some of you didn't were were born in other places but this is a classic expression heard in the United States all right now I'm going to tell you how you can add apples and oranges two different things together so that you could go back to your third grade second or third grade arithmetic teacher and explain how you can add apples and oranges you can add them together if you call them by a name that includes both apples and oranges what's the word that includes both apples and oranges fruit so if Johnny has three apples that's three fruit and Billy has two oranges that's two fruit so what do they have together five fruit now we can add apples to oranges every follow that this so uh in this example I talk about having three apples two oranges five bananas and one peach or a total of 11 fruits in the bowl so here's where we're going with this and I tell just mention it and then we'll explain this better after the break if we put one mole of glucose in the water and then we also put a mole of protein in the water well if we want to know what's the total amount of chemicals or solutes we put in the water we've got one mole of glucose and one mole of protein but the we have the problem you can't add glucose to protein they're two different things it's like trying to add apples to oranges so if we can't add a mole of glucose to a mole of protein because they're two different things we need to use a term that's broader than mole and the term we use is Oso it's like fruit so what we're going to learn after the break is that if you had one mole of glucose that's one Oso and if we had one mole of protein that's one osmo so one mole of glucose and one mole of protein is two osmol of solute particles this will allow us to calculate the total number of solute particles in a liter of water and by definition that's called its tonicity so we'll be able to quantify it that way so that's the purpose of this unit and the uh last thing I'll just point out or show you every single solution you look at every single one will indicate the number of milliosmoles and right here this solution says I know it's hard to read 46 milliosmoles per liter uh every single solu here's the one that's easier to read just because it shows up better this is four 447 milliosmoles per liter every single solution will have this written on here this is 308 milliosmoles per liter that is the way of quantifying the tonicity so we're going to explain what exactly this means and so we explained that uh the word osmo uh which is a contraction of the word osmosis and mold uh is very similar to this idea of fruit and it allows us to add apples and oranges or in this case moles of different chemicals together so if we look on page 11 on page 11 we're going to show you how we can calculate the tonicity of a solution containing many different chemicals so we're going to actually calculate the tonicity of a solution containing many different chemicals so let's imagine we took uh a liter of water 1,000 milliliters of water and we added the following chemicals right we uh added 140 milles of salt to a liter of water we added four milles of potassium chloride we added 2 milles of calcium chloride we added 5 m mes of glucose and 1 M protein and your first thought is what a mess okay so you added all those weird chemicals what is what have you made we've actually made a solution that is very much like blood plasma because that's about the concentrations of salt of sodium and potassium and calcium and glucose and protein in real blood plasma so it wasn't just a totally arbitrary solution now in order before we can figure out what the total number of solute particles are in this solution which is called its tonicity I want to remind you of a a major difference between organic and inorganic chemicals salt is an inorganic chemical glucose C6 h126 uh is an organic what's an organic a hydrocarbon made up of mostly carbon and hydrogen inorganic chemicals like salt what holds the atoms together are what kind of bonds ionic ionic bonds which is simply an electrical attraction between ions and when you add a molecule that is uh where the atoms are held together by an ionic bond into water it disassociates or ionizes it breaks apart forming sodium ions and chloride so when you put a salt molecule in water you don't have a salt molecule floating in the water you have separate sodium ions and chloride ions floating in the water now in contrast what kind of bond holds organic molecules carbon and hydrogen atoms together Co valent Co valent is a sharing of electrons and in general when you put molecules held together by Cove valent bonds into water it does not break apart if it breaks apart at all it's ever so slight and so uh usually doesn't break apart or just associate at all so when you drop a glucose molecule in the water you have a glucose molecule floating in the water so this is important because it affects the total number of solute particles that are formed in those of you had chemistry so you remember you had to learn you had to do problem sets dealing with what we called the K disassociation constants right anybody remember that where you had to calculate based on to what percent or degree it disassociates all right now let's go through each of these chemicals that we're adding to the water and take into account when we add that molecule to the water what happens to that molecule so in the first case we're adding 140 milles of salt 140 milles of salt remember since every salt molecule that we put in water actually dissociates or breaks apart into two solute particles if we're putting 140 milles of salt and if you don't like the word Millo just say 140 dozen so we're going to multiply that times two so uh what we actually have when you put 140 moles of salt in water is you end up with 140 milles of sodium ions and 140 milles of chloride ions for a total of 280 millios moles of solute particles again if in a chemistry class they would just say one Mo of salt forms one Mo of sodium ions and one Mo of chloride ions or two we would say two osmol uh all right now uh what about potassium chloride well first of all is KCl potassium chloride is that organic or inorganic it's inorganic it's not an organic molecule doesn't have any carbon and hydrogen so we predict that it's going to disassociate in General inorganic molecules do ionize or disassociate when added to water potassium chloride disassociates very much like salt into pottassium ions and chloride ions each potassium chloride forms two solute particles so if we put four milles of potassium chloride we multiply times two and we end up with 8 milliosmoles of particles because again what we actually have is four Mill moles of potassium chloride dividing into four Mill moles of potassium and four milles of chloride or 8 mosmos of particles again why are we using the word Osmos so that we can add all these different unrelated chemicals together it's like fruit now calcium chloride is calcium chloride ca2 is that organic or inorganic inorganic it's not an organic molecule it's not a hydrocarbon molecule so when you put it in water it actually dissociates into a c one calcium and two separate chloride so you should have learned that in chemistry but whether you did or didn't you know it now so uh if uh for every calcium chloride molecule we put in water we actually end up with three solute particles so we're going to multiply the number of Mill moles times three and we get six millios moles of solute particles okay now we also put glucose into this solution so is glucose organic or inorganic it's organic oric and in general organic molecules either don't break apart at all or just slightly and uh so we basically have U if we put five mill moles of glucose in the water we multiply times one because each glucose stays just one particle so we have 5 millios moles of solute particles and finally protein so uh I didn't specify what protein we put in the water so here I used the example example of albumin in fact I said that the solution we are making is very similar to real blood plasma and in fact the major protein in blood plasma is albumin you might say well isn't albumin like egg whites it is the major protein in our blood plasma is albumin now albumin protein uh is an organic molecule when you put it in water it it only slightly ever so slightly disassociates so pretty much it remains one solute particle so if we put one mill protein in we multiply time one and we have one millios so now let's add up all the mosmos of solute particles that are in this solution all right so what do we have starting at the top we have 10 280 milliosmoles due to Salt 8 milliosmoles due to potassium chloride six milliosmoles let me do this 280 and plus 8 is 288 plus 6 milliosmoles due to calcium chloride that's 294 plus 5 milliosmoles due to glucose that's 299 plus one mosmo due to protein is 300 so I calculated that the total number of solute particles in this liter of solution is 300 millios moles of solute particles so uh on page 12 we wrote at the top the solution we've just described has a total solute concent ation or tonicity of 300 milliosmoles per liter or 300 millios Moler and then I wrote right below the Box normal blood plasma has a total solute concentration or tonicity of 300 milliosmoles per liter therefore by definition any solution that also has a total solute concentration of 300 millios moles per liter is isotonic with blood plasma so it has the same solute concentration as blood plasma so now we know what the definition of isotonic is it is any solution that has a total solute concentration or tonicity of about 300 milliosmoles per liter now in the Box commonly in in hospitals instead of talking about the number of Milos moles of solute particles per liter of fluid they commonly talk about the number of milliosmoles of solute particles per kilogram fluid so you might say what let me ask you a question one liter of fluid weighs how much kilog one kilogram so in other words it's very common in hospitals to express this in mosmos per liter uh instead of mosmos per liter to express it in mosos per kilogram by weight but a kilogram of fluid by weight is one liter of fluid by volume so they mean the same thing um now you might as I talk about this unit you might say I never heard of this unit I've already shown you that that unit appears on every solution that is administered in the hospital but look at the bottom lab form okay this bottom lab form which I stole from which hospital what does it say this is Kaiser Peretti now on the top left of this form right it's it's analyzing blood plasma and it's telling us what the this is where the in the lab report they would describe the amount of sodium and pottassium and chloride electrolytes are in the blood plasma and notice the units are in Milly equivalents per liter but that's not what we're talking about on the lower right on this form can everybody see the term osmolality now osmolality is the term we use when we express the number of milliosmoles per kilogram so in other words if they call it uh if they talk about milliosmoles per liter they call it osmolarity if they talk about Milli Osmos per kilogram they call it osmolality I had written that right up above right here everybody see it milliosmoles per liter is Milli osmolar milliosmoles per kilogram is mosmol or osmolality we're going to use the terms interchangeably all right so on the lab form this is where they are measuring the osmolality or osmolarity of the blood plasma and according to Kaiser Peretti the normal tonicity or osmolarity or osmolality of blood is somewhere between 280 to 305 milliosmoles per kilogram or Mill per liter can we round that off and say it's about 300 all right that's what we're going to say it's about 300 so that's the normal acceptable range if the osmolarity or tonicity becomes less than 280 the person's body fluids are hypotonic if they become greater than 305 they are hypertonic You' say could you say that again I wrote it on page 14 on page 14 at the top any solution any solution we wrote on page 14 that has a total solute concentration less than 300 M osmoses per liter is hypotonic any solu that has a total solute concentration or tonicity greater than 300 millios per liter is hypertonic so now we can quantify how not only how hypotonic or how hyper iic our body fluids are we can quantify the tonicity of any solution and that's what we're going to ask you to do on page 15 so on page 15 we wrote that on page 15 for each of the following Solutions compute its total solute concentration or osmolarity in milliosmoles per liter and secondly indicate whether it's hypo ISO or hyperonic all right now uh just in terms of uh in in terms of uh hypo ISO or hypertonic that's really simple because once you've calculated the number of milliosmoles per liter if it's 300 it's isotonic if it's significantly lower than 300 it's hypotonic if it's significantly greater than 300 it's hypertonic so the second part becomes really simple so uh let's just do the first one for you uh the first one says say uh here we want to compute the total solute concentration or osity of a 150 Millar salt solution now remember in this question we're not asking you how would you make this solution inally 150 Millar salt solution is the same as 0.15 M earlier today we showed you exactly how to prepare a 0.15 m salt solution all right so so here I'm not asking you to calculate how many grams of salt you dissolve in a liter of water that's not what we're asking we want to know the total number of solute particles you'd say yeah like how do you do that when you add salt to water doesn't it break apart into two solute particles just say yes yes okay good so uh we didn't add one salt molecule we added 150 milles of salt because that's what's in 150 Mill salt solution so if you take 150 milles and each salt molecule breaks apart into two solute particles we multiply times two because we actually end up with 150 milles of sodium and 150 milles of chloride or a total of 300 milliosmoles of particles per liter so the tonicity of this solution of a 150 Mill salt solution is it contains 300 milliosmoles per liter so is it hypo ISO or hyperonic is it's isotonic and in fact just taking a look at this solution we've looked at earlier today all right 0.9% salt solution you'll notice this it says the marity is 308 milliosmoles per we just calculated 300 all right so this that was rounded off this is 308 mosmos this is isotonic and incidentally in it it's got 154 mil equivalents per liter of sodium and 154 mil equivalent of chloride 154 mil equivalent of sodium would be how many mill moles do we talk about converting from Mill moles to Mill equivalence and M equivalence to Mill moles to go from Mill moles to mil equivalence we multiply times the valence to go backwards for M equivalent to Mill Mo we divide by the veence what's the veence of sodium one well let's say you can't you know you you should remember how to go you know if you're going from Mil Mo to Millie equivalent you need to multiply times the veilance if you're going backwards you need to divide let's say you can't remember if it's a veilance of one it doesn't matter because whether you multiply times one or divide by one it's the same damn number so 154 Milli equivalents per liter is 154 mli moles per liter it's 1 into 150 is 150 154 so uh this is really saying you've got 154 Mill moles of sodium and 154 Mill moles of chloride or a total of 308 mosal exactly what we're talking about again I'm sure that some of you might have been in a clinical setting and handled these Solutions and you've never even noticed all this stuff written on them but you know there's a patter that what we all do is when we are looking at something we don't understand we ignore it so if we don't understand what it means then we just ignore that it's even there but it's all this information is on every one of these Solutions and you should understand what it is you're giving to somebody you'd say well what if I don't understand what I'm giving can I just give it you may be giving the wrong thing because you don't understand enough without what you're doing uh one of the questions that we've asked you to do one of the questions that we've asked you to do is to determine the tonicity of a 300 Millar sodium bicarbonate solution now first off why is sodium bicarbonate important why would it be given clinically it's a buffer all right so it's given for people with acid osis or alkalosis and there are all kinds of reasons why people develop acidosis and alkalosis all right but uh you you you may or may not know what sodium bicarbonate does when you put it in water here's what it does so if you didn't know we're going to explain it when you put sodium bicarbonate in water it does an interesting thing it disassociates into sodium ion and bicarbonate ion what's kind of interesting about sodium bicarbonate is that the sodium in sodium bicarbonate kind of reminds us of sodium chloride or salt which is inorganic but the bicarbonate made up of hydrogen carbon and oxygen looks like an organic molecule and in general organic molecules don't break apart so in fact that's exactly how it behaves the sodium which is like a sodium chloride breaks apart but the rest of it which looks like an organic molecule all stays together so each sodium bicarbonate disassociates into two solute parts particles all right and the last thing I just wanted to mention is that in this last solution we asked you to try called a modified ringer solution so it's got 140 milles of salt four milles of potassium chloride four milles of calcium chloride in a liter of solution all mixed together now you might say wait a second that's really complicated actually back on page 11 on page 11 I showed you a much more complicated solution a solution with five different chemicals in a liter of water so that's an easier one which only has three different chemicals I've already shown you how to calculate the total solum concentration if it's got five different chemicals so just try it all right in addition I want to remind you that you've got more problems on uh page 16 some of you I know have already started doing all right and I gave you a second handout today as well didn't I if you came in late I passed out you get it at the at the end of class A another set of problems