What is the role of thyroid hormones in metabolism?

The correct answer emphasizes that thyroid hormones play a critical role in regulating both cell growth and metabolism. Thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3), influence the metabolic processes of nearly every tissue in the body. They increase the basal metabolic rate, which means they boost the body's energy expenditure, facilitating greater oxygen consumption and heat production. In addition to their effects on overall metabolism, these hormones support cell growth and development, highlighting their vital contribution to normal growth and homeostasis.

The other options do not encapsulate the full range of functions of thyroid hormones. While option A states that thyroid hormones decrease metabolic rate, this fundamentally misrepresents their function. Option C suggests that thyroid hormones only impact carbohydrate metabolism, disregarding their broader role in lipid and protein metabolism as well. Lastly, option D focuses solely on calcium regulation, which is primarily managed by parathyroid hormone and does not reflect the comprehensive metabolic effects of the thyroid hormones. Therefore, recognizing the correct answer enhances understanding of the multifaceted role of thyroid hormones in maintaining metabolic balance and supporting growth.