hey guys it's miracles is perfection Alice this is the fifth video in our series about fluids electrolytes and acid-base disturbance in the previous video we have talked about osmosis osmotic pressure osmoles and osmolality Leyla's compare between osmolarity and osmolarity and let's get started [Music] if you can't explain it simply you don't understand it well enough very well said let me answer the questions of the previous video okay here is zero time and what do you think equilibrium is gonna be if there are more solute in column a than B then water is gonna shift from B to a so B should decrease below the zero level and a should increase above the zero level so the correct answer here is e second question calculate the osmolality of a solution in each case so her here we have one liter and one mole of sodium chloride is it ionizable yes it gives you sodium and chloride the answers to Oz moles per liter one mole of glucose in half a liter is glucose ionizable note it will give you 1 mole per half a liter but then for later is gonna be 2 and here you have one mole of calcium chloride it's gonna give you calcium chloride and chloride so 3 oz moles and 6 moles of sodium chloride 6 times 2 they're gonna give you 12 12 plus 3 equals 15 but we have 500 CC which is equal to half a liter you idiots so the correct answer here is 15 s time 2 is 30 so membrane transported either passive or active osmosis is passive simple diffusion as I've told you in the previous video osmosis is a simple diffusion of water from high concentration of water to low concentration of water or from low concentration of solute to high concentration of solute osmotic pressure the pressure needed to stop osmosis and we have talked about Avogadro and the mall and we know that chlorides ionizable it's gonna give you 2 oz moles and this is what we care about the number of molecules the number of Oz moles not the mass now osmolarity is the amount of force per volume measured in millions moles per kilogram per kilogram so what about osmolarity it's gonna be per liter per liter it's as simple as that but is there a mnemonic to remember it of course there is but first let's get the definition of molarity number of osmoles of a solute in a kilogram of solvent osmolarity the number of oz moles of a solid in a liter of solvent so the mnemonic goes like this a small lab RIT and delete turtle okay it's an auditory mnemonic because some of you will screw it up and say osmolarity has an L and later has a Nelson no no don't ruin it it's an auditory in the Monica listen to me a small error already by the liter er okay you will never forget it I hope so oz molarity per kilogram osmolarity per liter and the beauty of this mnemonic is that it works in the UK with the right leader like this and force in the US where the right leader like this okay this mnemonic works across cultures it's amazing which one is more accurate osmolality or osmolarity the answer is osmolality why osmolarity is in a kilogram and your weight doesn't change so for example let's get a test tube that contains fluid let's heat this fluid what's gonna happen to the volume the volume is gonna increase what's gonna happen to the weight it's not gonna change that's why as molarity the weight doesn't change osmolarity is more accurate now go to osmolarity and the liter if you hit a solution it will expand and the solution will look bigger the volume is going to increase so osmolarity is not the accurate one okay which one's more practical of course osmolarity because the measures in the liter why is that because let's say that you're a doctor and you told the nurse please get me a sample of blood or a sample of saline or whatever which one is easier to tell her get me 100 grams of the fluid or one hundred cc's of the fluid of course the easier is to get the volume we use like graduated stuff even the blood bags like have this stuff the syringes okay have the stuff okay so it's very easy to do it by the volume that's why a small rarity in the liter is more practical and as doctors we couldn't care less we call it osmolarity osmolality nobody gives a hoot so the difference between osmolality and osmolarity is BS or as they said in the UK it's nonsense osmolality in kilogram osmolarity in the liter which one is more accurate osmolarity which one's more practical osmolarity if you ask a clinician we couldn't care less about the difference between osmolarity or osmolarity we use them interchangeably and three remember it's doctor with edema due to increased hydrostatic pressure Qwest time on his first day in the hospital a crazy medical student administers 100% water to a patient instead of normal saline normal saline of course is a salt solution what are the consequences of his stupidity is it a or B C's will shrink B or B C's will swell and burst say serum sodium concentration will increase the total body sodium will decrease or a nothing it's the first day for the dude calm down have mercy on the dude no he's stupid did you know that now you can go to my patreon page click on video notes and choose hematology for example you will see all of my hematology notes there are like 150 of them you can download them print them view them do whatever you want go to patreon.com/crashcourse