Friday 07th January 2022
Group 2, Sub Group 3
EFFECTS OF VARIOUS CONCENTRATIONS OF ELECTROLYTES AND NONELECTROLYTES SUBSTANCES ON ERYTHROCYTES
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Aim: To determine the effects of various concentrations of electrolyte and non-electrolyte medium on hemolysis.
Principle: Small volumes of blood are mixed with a large excess of buffered solutions of NaCl of varying
concentration. The fraction of red cells lysed at each NaCl concentration is determined colorimetrically. The
experiment is carried out at room temperature (25  C).
Materials and method
A control heparin tube and 5 heparin tubes for NaCl were prepared using test tubes.
2mL of distilled water was placed in the control tube.
The 5 heparin tubes were coated with an anticoagulant (heparin).
2mL of the solution of NaCl was placed in each of the 5 heparin tubes, after the concentration in g/L was
calculated for each tube.
The result was written on a sheet of paper.
A drop of fresh human blood (non-hemolyzed blood) was added to each of the 5 heparin tubes.
The tubes were clogged and mixed gently by inverting them several times immediately, avoiding foam.
The mixture was allowed to rest for 10 minutes
The presence of hemolysis was tested in each tube by placing them in front of a printed sheet.
Hemolysis was present in tubes we could see through and absent in those we couldn’t.
Results
Tubes
Solutions
Molarities
Conc(g/L)
Observation
Control
Tube
H2O
0.00
0
Hemolysis
1
2
3
4
5
NaCl
0.03
1.75
Hemolysis
NaCl
0.06
3.51
Hemolysis
NaCl
0.12
7.01
No Hemolysis
NaCl
0.15
8,77
No Hemolysis
NaCl
0.18
10.52
No Hemolysis
Observations
In the control tube and tubes 1 and 2, hemolysis was recorded, with the control tube having the most hemolysis.
Whereas in tubes 3, 4, and 5, no hemolysis was recorded, with tube 5 being the most opaque of the three. The opacity
of the mixture in the tubes increased as we moved from the control tube to heparin tube number 5.
Explanation
The decrease in hemolysis as we moved from the control tube to heparin tube 5 is due to an increase in
concentration of solute (NaCl) in the eternal milieu of the cells. Influx of water increases as the concentration of the
external milieu decreases. So in the control tube, the cells are considered to be in a 100% hypotonic solution were
100% hemolysis occurred.
Discussion
Solutions of NaCl having concentrations of 1.75 and 3.51g/L, produced hemolysis. This is because at said
concentrations water moves into the cell at a faster rate than it exits since the solution is hypotonic to the cell. This
influx of water molecules leads to the swelling of the cell wall and ultimately to cell lysis.
Cells are considered isotonic when placed in a solution of NaCl having a concentration of 9g/L. At this
concentration the influx and efflux of water in the cell is equal thus keeping the cell volume constant.
The internal milieu helps to maintain osmotic pressure by having a similar electrolyte concentration to the body
plasma. So the amount of NaCl in the internal milieu is about 9g/L to match the concentration in blood plasma.
Osmolarity of control tube=2×molarity of NaCl=2×(moles of NaCl ÷ volume of solution)=2 × 0.00mol/L =0.00mol/L
Osmolarity of tube 5
=2×molarity of NaCl=2×(moles of NaCl ÷ volume of solution)=2 × 0.18mol/L =0.36mol/L
Osmotic pressure of control tube,∏=iMRT= 1.7i' × 0.00mol/L × 0.08206L atm mol-1 K-1 × 298.15K = 0.00Pa
Osmotic pressure of tube 5
,∏=iMRT= 1.7i' × 0.18mol/L × 0.08206L atm mol-1 K-1 × 298.15K = 7.49Pa
References
https://www.bionity.com/en/encyclopedia/Saline_%28medicine%29.html
http://www.medicine.mcgill.ca/physio/vlab/bloodlab/eryfrag1_n.htm