The basal metabolic rate (BMR) in body cells is regulated by :

Options

A. Parathyroid
B. Thyroid
C. Pituitary
D. Thymus

Answer

**Step-by-Step Solution:**

1. **Understanding Basal Metabolic Rate (BMR):**
- The Basal Metabolic Rate (BMR) refers to the rate at which our body expends energy at rest to maintain vital functions such as breathing, circulation, and cell production.

2. **Identifying the Glands Involved:**
- The question lists four glands: parathyroid, thyroid, pituitary, and hypothalamus. We need to determine which of these regulates BMR.

3. **Analyzing the Parathyroid Gland:**
- The parathyroid gland is located behind the thyroid gland and primarily regulates calcium levels in the blood through the secretion of parathyroid hormone (PTH). It does not play a role in regulating BMR.

4. **Examining the Thyroid Gland:**
- The thyroid gland produces hormones such as thyroxine (T4) and triiodothyronine (T3). These hormones are crucial for regulating metabolism, including BMR. They influence the metabolic rate of cells and are directly responsible for the energy expenditure in the body.

5. **Considering the Pituitary Gland:**
- The pituitary gland releases various hormones, including Thyroid Stimulating Hormone (TSH), which stimulates the thyroid gland to produce T3 and T4. However, the pituitary gland itself does not directly regulate BMR; it influences the thyroid gland.

6. **Looking at the Hypothalamus:**
- The hypothalamus plays a role in regulating many bodily functions, including the endocrine system, but it does not directly regulate BMR. It can influence the pituitary gland, which in turn affects the thyroid gland.

7. **Conclusion:**
- Based on the analysis, the thyroid gland is the primary regulator of the basal metabolic rate in body cells through the secretion of T3 and T4 hormones. Therefore, the correct answer is the thyroid gland.

**Final Answer:**
The basal metabolic rate (BMR) in body cells is regulated by the thyroid gland.

---