Kaplan Nursing Entrance Practice Exam

What primary role do thyroid hormones play in the body?

1. Regulation of blood pressure

2. Regulation of metabolism

3. Regulation of immune response

4. Regulation of muscle contractions

The correct answer is: Regulation of metabolism

Thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3), are crucial in regulating metabolism within the body. These hormones influence how the body utilizes energy, affects the rate of metabolism, and helps control the speed at which the body's cells convert oxygen and calories into energy. When thyroid hormone levels are optimal, they help maintain a balance between energy production and energy expenditure, impacting various bodily functions such as growth, repair, and overall energy levels. Thyroid hormones also play a significant role in regulating basal metabolic rate, which is the rate at which the body uses energy while at rest. This means that even small fluctuations in thyroid hormone levels can lead to changes in weight, energy levels, and overall metabolic health. While the other options pertain to important physiological processes, they do not capture the primary function of thyroid hormones. Blood pressure regulation involves multiple systems, including the cardiovascular and nervous systems; immune response is primarily mediated by the immune system and related hormones; and muscle contractions depend mainly on calcium and nerve impulses. Thus, the distinctive role of thyroid hormones is best characterized by their primary responsibility for regulating metabolism.