 Hi, let us see what would be the effect on ICF and ECF osmolarity if a fluid of varying osmolarity is added into the body clothes. So this is basically understood by means of Darrow-Yannett diagrams and these diagrams basically represent the osmolarity of ECF and ICF and the volume of ECF-ICF in a graph format and then what are the changes in these osmolarity and volume when any fluid is added that is represented further by changes in this graph. So basically Darrow-Yannett diagrams usually explain the effect on ICF and ECF osmolarity and volume with addition laws of fluid of various fluids that is the isotonic, hypertonic or hypertonic fluids. So first let us see basic Darrow-Yannett diagrams in the physiological condition. So here if you see the X axis shows the volume okay and the Y axis shows the osmolarity and basically this axis can extend right so volume can decrease also or ICF volume can increase also so in that case we have to shift it to this particular side and the ECF volume can also decrease or increase. So this full is determined as volume and if you see the graph now ICF represents two-third of total body water. So this outer border determines the is representing the total body water then this total body water is divided into two-third and one-third by means of this central line. So this is representing ICF and this is part is representing ECF okay and basically you see the volume is different of ICF and ECF but osmolarity of ICF, ECF is same okay more or less ICF and ECF osmolarity is same and what happens that if any hypertonic or hypertonic fluid is added then it is the movement of the water which occurs across the membrane between ECF and ICF and ultimately the osmolarity of ICF and ECF will also become same even if addition of some hypertonic or hypertonic fluid is occurring. So let us see what will be the changes of ECF and ICF osmolarity and volume with the addition of various fluids. Now suppose isotronic fluid is added right so 0.9 percent NCL is an example of isotronic fluid basically with the tonicity same as that of the plasma so if that is added so obviously addition will be in the ECF you cannot take out all the cells separate out all the cells and inject any fluid so first you have to understand that whatever fluid is being added first changes will be occurring in the ECF right so isotronic NCL if it is added what is the osmolarity osmolarity is same as that of the body fluids right so here what we will see is that osmolarity no change okay of the ECF right but because the fluid is added in the ECF what will happen that the volume of ECF is going to increase what about the volume of ICF well there will be no change because the fluid added is isotronic okay and movement of water will occur between the compartments if there is a change in the osmolarity right so ICF compartment will remain same only the ECF compartment will extend right so that is the change which will happen in the volume of the ECF and osmolarity of both the compartments will remain same now with the similar logic what will happen if there is loss of isotronic fluid if there is loss of isotronic fluid again the loss will occur from which compartment from the ECF compartment right so ECF compartment is going to reduce and since it is isotronic no fluid movement will occur from ICF to ECF or ECF to ICF right so osmolarity is same osmolarity is the driving force for water so since it is same only there will be reduction in the volume of ECF while ICF compartment will remain same so if we draw the changes ICF is the same volume see no change in volume right and the ECF compartment has reduced while the osmolarity in the y axis it is same which was before coming to the third right so now things are going to become little complicated let us see so we will go step by step so that you understand the concept and you are able to simplify it for yourself also so now let us add hypotonic fluid okay and where will it be at obviously in ECF so what is going to happen that with the addition of the fluid with the addition of the fluid ECF volume is going to increase we are adding the fluid isn't it ECF volume is going to increase what will happen to osmolarity since it is a hypotonic fluid right so suppose before osmolarity was 300 and now we add a fluid whose osmolarity is 250 so somewhere in between the osmolarity will come say suppose 275 right so osmolarity of ECF is going to decrease with the addition of hypotonic fluid now you see that the osmolarity of ECF has become less than that of ICF so now water movement will occur and from where to where water movement occurs from the area of hypotonicity to the area of hypotonicity right from the area of less osmolarity to more osmolarity where more solutes are there so water movement will start occurring into ICF so what will happen ICF volume is going to increase right and what will happen to osmolarity because water movement is occurring osmolarity of ICF also is going to decrease the movement of water is going to decrease ICF osmolarity as well and ultimately the osmolarity of the two compartments will become same understanding so this osmolarity it will decrease like this okay and what has happened to volume volume has increased ECF volume has increased because we have added the fluid okay and ICF volume also has increased now one thing which volume is going to increase more is it ICF volume or ECF volume well the water distributes in proportion to the size of the compartment then only equilibrium of osmolarity is going to occur understanding so if suppose two liter fluid is added two-thirds of this fluid will move into ICF because it is made up of two-third of total body water so ICF compartment is going to increase more compared to the ECF compartment and movement of water basically continues till the osmolarity of both the compartments becomes same so with the addition of hypotonic fluid both the compartments volume increases and both the compartments osmolarity decreases coming to next that is the loss of hypotonic fluid what is going to happen now you apply the same logic what is going to happen first of all fluid is getting lost so from which compartment it is getting lost from ECF right so ECF volume what will happen it is going to decrease what about osmolarity of ECF because hypotonic fluid is being lost that means more of water and less of solutes are being lost osmolarity in the compartment is going to increase okay so what we are going to draw is that volume is decreasing like this and osmolarity is increasing so osmolarity is going to increase right then coming to ICF what will happen obviously you see that because the osmolarity of ECF has increased water will move from now ICF to ECF from low osmolarity to high osmolarity so yes what was there in the beginning that will not be the case there will be a little bit volume it will kind of become here right and ICF compartment is also going to decrease in volume because water is moving from ICF to ECF right what about the osmolarity in ICF well because the water is moving into ECF only water and not solutes the osmolarity in ICF also is going to increase okay so this is what is going to become the final result so that is the osmolarity of both the compartments is increasing and the volume of both the compartments is decreasing so just quickly you see the summary when we add hypotonic fluid both the compartments increase in volume and osmolarity decreases when there is loss of hypotonic fluid both the compartment decrease in volume and there is increase in osmolarity coming to next that is adding hypotonic solution so go step by step again if we add hypotonic solution to ECF what will happen to volume we are adding the solution ECF volume is going to increase right and since it is a hypotonic solution osmolarity is also going to increase so let us draw it volume will extend like this right and osmolarity also going to increase like this then water movement will occur because of the change in osmolarity osmolarity outside in ECF is more so water will move from ICF to ECF so ICF volume is going to decrease okay so it will shift this side right it only may be this much ICF volume is remaining but osmolarity is going to increase right osmolarity will be same ultimately in both the compartments so osmolarity is going to increase so this will be the result on adding hypotonic solution fine moving to the last example hopefully you will be able to solve it on your own loss of hypotonic solution so it is moving out from ECF right so ECF volume what will happen ECF volume is going to decrease hypotonic solution is being lost that means more of solutes are being lost less of water so osmolarity is going to decrease then decrease osmolarity will cause movement of the water from ECF to ICF right so ICF volume is going to increase right and osmolarity again it is going to decrease because solutes will be diluted by water right so let us draw it here ECF volume decrease like this right osmolarity decreased in both so it will be like this right it has come down and volume increase so is ICF volume will increase so it will be like this okay so this will be the end result of loss of hypotonic solution thanks for watching the video if you liked it do press the like button share the video with others and don't forget to subscribe to the channel physiology open thank you