Primary function of sweat is -----------

Answer

**Step-by-Step Solution:**

1. **Understanding Sweat Composition**: Sweat is primarily composed of water, salts (like sodium chloride), lactic acid, and small amounts of urea.

2. **Identifying the Function of Sweat**: The main function of sweat is to regulate body temperature. When sweat evaporates from the skin surface, it cools the body down.

3. **Evaporative Cooling Mechanism**: The process of evaporation requires heat, which is taken from the skin. This heat loss results in a cooling effect, helping to maintain a constant body temperature.

4. **Accessory Functions of Sweat**: Although the primary function is cooling, sweat also plays a role in excretion. It helps eliminate some waste products such as urea, salts, and lactic acid from the body.

5. **Conclusion**: Therefore, the primary function of sweat is to provide a cooling effect through evaporation, while it also serves an accessory role in excretion.

**Final Answer**: The primary function of sweat is to provide a cooling effect.

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