Hypertonic, Hypotonic, and Isotonic Solutions

Solutions and Their Effects on Cells

• Introduction to Solutions and Cells

  • Example: Three containers with saltwater solutions and a giant cell placed in each.

  • Importance of understanding tonicity: hypertonic, hypotonic, isotonic.

Identifying Tonicity

• Isotonic Solution

  • Middle container is isotonic.

  • Definition: Solute concentration outside the cell equals solute concentration inside the cell.

• Hypertonic Solution

  • Left container is hypertonic.

  • Definition: Solute concentration outside the cell is greater than inside the cell.

    • The "hyper" prefix signifies higher.

• Hypotonic Solution

  • Right container is hypotonic.

  • Definition: Solute concentration outside the cell is less than inside the cell.

    • The "hypo" prefix signifies lower.

Concentration and Water Movement

• Relationship between solute concentration and water concentration:

  • High saline concentration = low water concentration.

  • Low solute concentration = high water concentration.

Cell Membrane and Osmosis

• Assumed semi-permeable membrane:

  • Allows water movement but not ions (sodium and chloride).

• Osmosis

  • Definition: Diffusion of water.

  • Movement of water: Higher to lower concentration, influenced by ion presence.

Effects of Solutions on Cells

• Hypertonic Solution Effects

  • Water flows out of the cell because outside concentration has lower water content.

  • Net movement of water: Outward, leading to cell shriveling (plasmolysis).

• Isotonic Solution Effects

  • Equal concentration of solutes inside and outside the cell.

  • Equal flow of water in both directions, resulting in no net movement.

  • Cell maintains its shape.

• Hypotonic Solution Effects

  • Outside solution has lower solute concentration and higher water concentration.

  • Water flows into the cell due to higher concentration of water outside than inside.

  • Cell swells and may burst, resulting in cytolysis.

Analyzing Water Movement

• Two perspectives on water movement:

  • From water concentration: High to low concentration.

  • From solute concentration: Water moves toward areas of high solute concentration.

Interaction of Water with Ions

• Water's polarity influences attraction to ions.

• Sodium ions:

  • Water's oxygen (partial negative charge) attracted to sodium (positive charge).

• Chloride ions:

  • Water's hydrogen (partial positive charge) attracted to chloride (negative charge).

Conclusion

• Summary of cellular response to different solutions:

  • Hypertonic = shriveling.

  • Isotonic = no change.

  • Hypotonic = swelling/bursting.

• Importance of tonicity in biological systems.