Isotonic, Hypertonic, and Hypotonic Solutions
Isotonic Solution:
An isotonic solution is one in which the concentration of solutes is the same both inside and outside the cell. This means that there is no net movement of water across the cell membrane, as the concentration of solutes is balanced. Cells placed in an isotonic solution will maintain their shape and size.
Hypertonic Solution:
A hypertonic solution is one in which the concentration of solutes is higher outside the cell compared to inside the cell. This creates a concentration gradient that causes water to move out of the cell, leading to cell shrinkage or crenation. Cells placed in a hypertonic solution will lose water and may shrivel up.
Hypotonic Solution:
A hypotonic solution is one in which the concentration of solutes is lower outside the cell compared to inside the cell. This creates a concentration gradient that causes water to move into the cell, leading to cell swelling or lysis. Cells placed in a hypotonic solution will take in water and may burst.

Key Differences:
- Isotonic solution has equal solute concentration inside and outside the cell, maintaining cell shape.
- Hypertonic solution has higher solute concentration outside the cell, causing cell shrinkage.
- Hypotonic solution has lower solute concentration outside the cell, causing cell swelling.
Understanding the differences between isotonic, hypertonic, and hypotonic solutions is crucial in various biological and medical contexts, such as understanding how cells maintain their shape and function in different environments.