The principal heat regulating centre is located in the:

Options

A. Sebaceous gland
B. Lungs
C. Epidermis
D. Hypothalamus

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks about the location of the principal heat regulating center in the body.

2. **Identifying the Heat Regulating Center**: The principal heat regulating center is responsible for maintaining the body’s temperature through various processes.

3. **Key Processes Involved**: The two main processes involved in heat regulation are:
- **Vasodilation**: This is the widening of blood vessels, which helps in heat loss.
- **Vasoconstriction**: This is the narrowing of blood vessels, which helps in heat retention or production.

4. **Locating the Center**: The structure in the brain that regulates these processes is the **hypothalamus**.

5. **Functions of the Hypothalamus**:
- The **anterior hypothalamus** is involved in vasodilation, promoting heat loss.
- The **posterior hypothalamus** is involved in vasoconstriction, promoting heat production.

6. **Conclusion**: Therefore, the principal heat regulating center is located in the **hypothalamus**.

**Final Answer**: The principal heat regulating centre is located in the hypothalamus.

---