Affect of Different Solidity Solutions on Hermatocrit Percent of Red Blood Cells


The purpose of this lab was to see how the red blood cells in the cow blood respond to different salt concentrated solutions. Whether the solution was hypertonic, hypotonic or isotonic compared to the concentration of the cell. Hypertonic is when the solute concentration in the solvent is higher then the concentration in the cell. Hypotonic is the opposite of hypertonic; this means that the solute concentration in the solution is lower then the concentration with in the cell. Isotonic is the median when the solute concentration with in the cell is in equilibrium with the solute concentration in the solvent1). These terms help define osmosis the process which defines the way water molecules moves from higher solute concentration to lower solute concentration through a permeable membrane. In attempts to reach equilibrium, or isotonic when the solute concentration is the same within the cell and the solution2).

The main purpose once the cells were placed in solutions with different NaCl concentrations was to see how they each affected the hematocrit percent of the red blood cells in eight different solutions that were used. Hermatocrit percent is the length of the packed cells in the hermatocit tube divided by the length of the packed cells plus the length of the supernatant time one hundred. This could be affected by which solutions the cells are placed in. My hypothesis is that the hermatocrit percent is going to be the biggest when the solute concentration is the closest to equilibrium and the further you get from that the less the hermatocrit percent is going to be. The reason for this is because if the solution is hypertonic the cells will crenate because all of the water will rush out and if the solution is hypotonic the cells will lyses because water will go into the cell and cause it to swell and lyses. As the red blood cells are being destroyed the hermatocrit percent decreases because there is less red blood cells to be packed.


In the experiment we mixed the 1 mL red blood cells (cow blood) in 2.5 mL of eight different solutions water, .075,.100,.125.154,.200,.300,.400 mol/1NaCl. Once we made our solutions they were gently mixed by tipping the covered tube several times as the solutions incubated in room temperature for 15 minutes. Then three replicate hematocrit tubes of each blood solution, then sealed with sealing wax. The tubes are then placed in the centrifuge and spun at medium speed to assist the cell in packing in the bottom of the hermatocrit tube. Then the hermatocit percent is calculated of each of the tubes.

Results and Discussion


(This table is our class results of our hermatocrit percent compared to the concentration of the solution that the red blood cells were placed in. The heights of the blue bars are the mean hematocrit percent at that concentration. The thin black bars are the error bars)

These results show us that the hermatocrit percent is the highest when the concentration of the solution was 0.154 M this is because at this concentration, the solution is isotonic with the cell. So none of the cells lyses nor crenate allowing for more red blood cells to be packed in the hermatocrit tube resulting in a higher hermatocrit percent. As the concentration is increased or decreased from 0.154 M the hermatocrit percent decreases this is because when the concentration of the solution decreases the solution goes into the cell by osmosis this causes the cells to swell and cause some to lyses which destroys some of the cells and causes the hermatocrit percent to decrease because there are less of them to be packed. There is a drastic decrease in the hermatocrit percent when the concentration went from .100 M to .075 M this is because the cells must have reached a threshold where the cells reach the most they can be expanded until they all lyses. To find exactly at what concentration the threshold is at we could have gone downward in smaller steps of concentration to find exactly where the threshold is. When the hermatocrit is 0 is because the cells all lyses and it was so rapid because the concentration gradient is so large (the larger the difference of concentration the larger the concentration gradient) which caused the cells to lyses violently and break up to tiny pieces. So none of the cells could be packed on the bottom so the hermatocit percent is zero.

When the concentration increases from .154 M the hermatocrit percent steadily decreases. This is because as the solute concentration of the solution increase from the isotonic state at .154M the fluids from the cell move out ward through osmosis. This causes the cells to shrivel and could shrivel so much to the extent that they are completely destroyed causing the hermatocrit percent to decrease. If the solution got more concentrated then what we tested we would see the threshold affect that we saw while going downwards and eventually reaching zero.

The error bars on the graph are shown the represent the variability of the classes data.


After this experiment was completed it proved that my hypothesis was correct. The one thing that I did not consider that happened in the experiment was the threshold effect that made the hermatocit percent drop rapidly. The results of the experiment show that the highest point of hermatocrit percent was when the solution was isotonic and as the solution was changed to hypertonic and hypotonic the hermatocrit percent began to decrease. The cells were distorted and destroyed causing the hermatocrit percent to decrease.


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