so here we have three containers with salt water solutions and in each container we placed a giant cell let's assume it's a one huge giant cell now looking at these three solutions which one is a hypertonic solution a hypotonic solution and an isotonic solution what would you say well we can easily spot the isotonic solution the word iso means the same so the one in the middle has to be an isotonic solution and the reason for this is because the concentration that i mean the solute concentration of the solution that is outside the cell is equal to the solid concentration of the solution inside the cell now which one is the hypertonic solution is it the one on the left or the one on the right it turns out that the solution on the left is a hypertonic solution now the reason why it's a hypertonic solution is because the solution on the outside has a higher solute concentration than the cell concentration inside i mean let me say that again because my words just didn't come out right so the solid concentration outside of the cell is greater than the solid concentration inside the cell so the solution on the outside is hypertonic to the solution on the inside because it has a higher solid concentration the word hyper means higher or above the other one has to be a hypotonic solution the word hypo means below or less than so the solution on the outside is hypotonic to the solution inside the cell as we can see zero one is less than point one so here are some notes that you can take for a hypertonic solution the concentration of the solution outside the cell is greater than the concentration of the solution inside the cell for an isotonic solution the concentration of the solution and the cell concentration are the same and for a hypotonic solution the concentration of the solution outside the cell is less than the concentration of the solution inside the cell now there's something that you need to understand when the saline concentration of the solution is high the water concentration of the solution will be low likewise when the solid concentration of the solution is low the water concentration of the solution will be high now in this example for the sake of simplicity let's assume that the cell membrane is semi-permeable let's assume that it allows water to flow into and out of the cell but not ions not the solute particles here we have a sodium chloride solution which is made up of sodium ions and chloride ions the sodium ions have a positive charge the chloride ions have a negative charge positively charged ions are known as cations negatively charged ions are known as anions now osmosis is the diffusion of water and diffusion is the net movement of particles from a region of high concentration to a region of low concentration so osmosis will cause water to flow from a region of high concentration to a region of low concentration down its gradient another way to look at this is that water being polar is attracted to these ions so water is going to flow to the solution with a higher concentration of ions so it's going to flow to this one so now let's see what's going to happen with each of these three different solutions so let's start with the hypertonic solution will water flow into or out of the cell what would you say it turns out that water flows in both directions the concentration of water inside the cell is high and the concentration of water outside the cell is low keep in mind a low solid concentration corresponds to a high concentration of water so water will have will be flowing out of the cell now keep in mind water while water is flowing out of the cell some water molecules are flowing into the cell however the net movement of water will be outside the cell as we can see there's more arrows pointed outward then inward so the net result is that water is coming out of the cell as a result the cell is going to shrivel it's going to get smaller and this process is known as plasmolysis now what about in the isotonic solution what's going to happen the concentration of water is the same inside the cell and outside the cell so water is going to be flowing outward and at the same time water is going to be flowing inward so there's no net movement of water into or out of the cell so thus the cell is going to maintain its shape so it's going to it's not going to shrivel up and it's not going to expand it's going to remain the same now what about in the hypotonic solution what's going to happen to the cell so if we place a cell in a hypotonic solution that is where the solution on the outside have a lower concentration of soggy particles than the solution on the inside water is going to flow from a region of high concentration to a region of lower water concentration so here the solid concentration is lower which means the water concentration is high outside the cell so it's low inside the cell so water is going to flow down its concentration gradient into the cell as that continues to happen the cell is going to swell it's going to get bigger and bigger as more and more water molecules continue to flow into the cell through membrane channels such as aquaporins now as the cell continues to swell it may even burst in a process known as cytolysis so that's what's going to happen if you place a cell in the hypotonic solution now when analyzing the direction of the net movement of water molecules you can look at it two ways you can analyze it from the perspective of the relative concentration of water which is what we did as you can see the arrow points from a high concentration of water to a low concentration of water or you could look at it with respect to the solid concentration the water is going to flow wherever there's a lot of ions it's going to flow into the compartment that has a high solid concentration so 0.5 is greater than 0.1 so water is going to flow outside of the cell towards the higher solid concentration here the solid concentration is the same so nothing is going to happen and here the solid concentration inside the cell is greater than what's outside the cell so water flows towards those ions and that makes sense because water is attracted to ions such as sodium and chloride so this is the molecular structure of water the oxygen has a partial negative charge and the hydrogen atoms has a partial positive charge sodium has a positive charge and so the oxygen part of water is attracted to sodium so it's going to flow towards it now in the case of chloride the hydrogen part of water is attracted to the chloride ions because of the electrostatic attraction opposite charges attract so hydrogen is attracted to chloride so let's go back to one of our pictures so let's say the concentration is 0.1 and here the concentration is 0.5 so on the outside there's a higher concentration of sodium and chloride ions thus water inside the cell is going to be attracted to those solu particles so that's going to be a driving force in terms of why water is going to leave the cell as water leaves the cell it's going to interact with the ions in the following way so the oxygen part of water is going to orient itself towards the sodium ion and so these water molecules will surround the sodium ion they all carry a partial negative charge that is the oxygen part of water and thus they stabilize this sodium ion and that electrostatic attraction that's what pulls water out of the cell towards the higher solid concentration in the case of chloride the hydrogen atoms in water will surround the chloride ion stabilizing it in the solution so this is known as hydration so each hydrogen atom in water has a partial positive charge and so they're going to interact with the negatively charged chloride ion that's stabilizing it and so natural systems will always look for ways to find the most stable conformation or the most stable situation and this water wants to lead the cell to go towards the side with a higher solid concentration it wants to interact with these sodium and chloride ions so that it could form the most stable situation and so that's it for this video now you know the difference between a hypertonic solution a hypotonic solution and an isotonic solution so keep keep this in mind whenever you place a cell in a hypertonic solution it's going to shrivel up and if you place the cell in the hypo tonic solution it's going to expand and swell so that's it for this video thanks again for watching