The erythrocytes undergo crenation due to

Options

A. Exosmosis
B. Endosmosis
C. Plasmolysis
D. none of these

Answer

### Step-by-Step Solution:

1. **Understanding Erythrocytes**: Erythrocytes, commonly known as red blood cells (RBCs), are responsible for transporting oxygen in the body. They have a biconcave shape that increases their surface area for gas exchange.

2. **Isotonic Condition**: In a healthy state, the concentration of solutes inside the erythrocytes is equal to the concentration of solutes in the surrounding fluid (isotonic condition). This balance allows for the free movement of water in and out of the cells without causing any change in their shape.

3. **Hypertonic Condition**: When erythrocytes are placed in a hypertonic solution (where the concentration of solutes outside the cell is higher than inside), the water potential outside the cell becomes lower than that inside the cell.

4. **Movement of Water**: Due to osmosis, water moves from an area of higher water potential (inside the cell) to an area of lower water potential (outside the cell). This results in a loss of water from the erythrocytes.

5. **Crenation**: As water leaves the erythrocytes, they begin to shrink and develop a spiked appearance. This process is known as crenation. The RBCs lose their normal shape and become distorted.

6. **Plasmolysis**: The term "plasmolysis" refers to the process where the cell membrane pulls away from the cell wall due to the loss of water. In the case of erythrocytes, this is specifically referred to as crenation when they shrink in a hypertonic solution.

7. **Conclusion**: Therefore, the erythrocytes undergo crenation due to the process of plasmolysis that occurs when they are placed in a hypertonic solution.

### Final Answer:
The erythrocytes undergo crenation due to **plasmolysis**.

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