video on globular resistance Salima TP nHematology.mp4

Study of Globular Resistance and Osmotic Effects
📌 The study investigates the resistance of globular cells (red blood cells/erythrocytes) to rupture when immersed in solutions with varying solute concentrations.
🩸 Red blood cells are anucleated cells filled with hemoglobin, which causes the surrounding liquid to turn red upon lysis (hemolysis).
🧪 The experiment measures the effect of different concentrations of NaCl (salt) and glucose (sugar) on water movement within the red blood cells, determining the concentrations that cause cell rupture.

Experimental Procedure and Observations
⚙️ The procedure involves setting up two series of tubes (seven each), one for glucose and one for NaCl, each containing $2 \text{ mL}$ of solution at decreasing molarity.
🔴 Two drops of red blood cell suspension are added to each tube, agitated, and allowed to rest for 30 minutes at ambient temperature (not exceeding $30^\circ \text{C}$).
📊 Hemolysis is indicated by a red supernatant, while the absence of hemolysis results in a colorless supernatant and a cell pellet (culot).
📉 For glucose, hemolysis began starting at a concentration of $0.110 \text{ M}$ (tubes 3 to 7 showed hemolysis).
🧂 For NaCl, hemolysis occurred at much lower concentrations, starting from $0.062 \text{ M}$ (tubes 4 to 7 showed hemolysis).

Osmotic Principles and Cell Behavior
💧 Water moves from the less concentrated medium (hypotonic) to the more concentrated medium (hypertonic) across the membrane to achieve hydraulic equilibrium, according to the law of osmosis.
🌊 In a hypotonic external medium, water enters the red blood cell, causing it to swell and potentially lyse (hemolysis), releasing hemoglobin.
🌵 In a hypertonic external medium, water exits the red blood cell, causing it to shrink (crenation). An isotonic medium results in no net water movement.

Results Interpretation and Dissociation Calculation
⚖️ Based on results, the concentration of glucose ($0.110 \text{ M}$) is isotonic with $\text{NaCl}$ at $0.062 \text{ M}$.
🔢 The ratio of concentrations required to cause hemolysis is approximately $1.77$ ($0.110 / 0.062 \approx 1.77$). This implies that 100 $\text{NaCl}$ molecules exert the same osmotic pressure as 177 glucose molecules.
⚗️ This difference is because $\text{NaCl}$ dissociates into two ions ($\text{Na}^+$ and $\text{Cl}^-$), while glucose does not dissociate. For $\text{NaCl}$ to fully dissociate, the osmotic pressure ratio should be $2:1$ (200 glucose molecules vs. 100 $\text{NaCl}$ molecules).
📊 By calculating the number of osmotically active particles, it was determined that only 77% of the $\text{NaCl}$ molecules actually dissociated in solution.

Key Points & Insights
➡️ Red blood cells are used to study membrane resistance by observing hemolysis when exposed to varying external osmotic pressures.
➡️ Glucose is non-dissociable, meaning its osmolarity equals its molarity ($Osmolarity = Molarity$).
➡️ $\text{NaCl}$ is dissociable; its theoretical osmolarity is double its molarity ($Osmolarity = 2 \times Molarity$) if dissociation is complete.
➡️ The experimental data confirmed that $\text{NaCl}$ only achieved 77% dissociation under these conditions, leading to an observed osmotic ratio of $1.77$ instead of the theoretical $2.0$.

📸 Video summarized with SummaryTube.com on Feb 27, 2026, 09:22 UTC