Which hormone is secreted by the thyroid gland?

• A. Thyroxine
• B. Insulin
• C. Adrenaline
• D. Testosterone

Answer: (A)

The hormone secreted by the thyroid gland is thyroxine, also known as T4. It plays a crucial role in regulating metabolism, influencing how the body uses energy, and is essential for normal growth and development. Thyroxine increases the basal metabolic rate (BMR), stimulates the heart, and supports the functioning of various organs in the body.

In contrast, insulin is produced by the pancreas and is responsible for regulating blood glucose levels. Adrenaline, or epinephrine, is secreted by the adrenal glands and is key in the body's fight-or-flight response, affecting heart rate and energy availability. Testosterone is primarily produced in the testes in males and ovaries in females, influencing male reproductive development and secondary sexual characteristics.

Understanding the role of thyroxine is vital for recognizing its impact on overall health, including metabolism and energy levels.