Which gland regulates growth and metabolism with hormones such as thyroxine?

• A. Pancreas
• B. Thyroid gland
• C. Adrenal
• D. Pituitary

Answer: (B)

The thyroid gland. It emits thyroid hormones, including thyroxine, which raise the body's baseline metabolic rate and drive energy use in nearly all tissues. This boosts metabolism of carbohydrates, fats, and proteins and increases heat production. Thyroxine also supports normal growth and development, especially in children. The system is regulated by the hypothalamus and pituitary: TRH from the hypothalamus prompts TSH from the pituitary, which stimulates the thyroid to release T4 (thyroxine) and T3, with T4 often being converted to the more active T3 in tissues. When thyroid hormone levels are off, growth and metabolism are affected—low levels slow growth and metabolic rate, while high levels raise them.