Explain the significance of sodium, potassium, magnesium and calcium on biological fluids.

Explanation

### Step-by-Step Solution:

1. **Sodium in Biological Fluids**:
- Sodium ions (Na⁺) are primarily found in plasma and the interstitial fluid surrounding cells.
- They are crucial for the transmission of nerve signals from the brain to various parts of the body.
- Sodium ions also facilitate the transportation of glucose and amino acids into cells, which is essential for energy production and overall metabolic processes.

2. **Potassium in Biological Fluids**:
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