BMR is increased due to :

Options

A. Sympathetic nervous system
B. Adrenaline
C. Parasympathetic nervous system
D. Thyroxine

Answer

To determine what causes an increase in Basal Metabolic Rate (BMR), we need to analyze the options provided: sympathetic nervous system, adrenaline, parasympathetic nervous system, and thyroxine.

**Step 1: Understand BMR**
- BMR stands for Basal Metabolic Rate, which is the rate at which the body expends energy at rest to maintain vital functions such as breathing, circulation, and cell production.

**Step 2: Identify the role of the thyroid gland**
- The thyroid gland plays a crucial role in regulating BMR through the secretion of hormones. The primary hormones involved are Tetraiodothyronine (Thyroxine or T4) and Triiodothyronine (T3).

**Step 3: Analyze the options**
- **Sympathetic Nervous System**: This part of the nervous system can increase metabolic activity, but it is not the primary regulator of BMR.
- **Adrenaline**: This hormone, released during stress or emergency situations, can temporarily increase metabolism but is not a direct regulator of BMR.
- **Parasympathetic Nervous System**: This system generally promotes rest and digestion, which would not increase BMR.
- **Thyroxine**: This hormone significantly influences BMR by increasing the metabolic rate of cells throughout the body.

**Step 4: Conclusion**
- Among the options provided, the hormone that directly increases BMR is **Thyroxine**. Therefore, the correct answer is **Thyroxine**.