Which metabolic change is most directly attributed to thyroid hormones?

Which metabolic change is most directly attributed to thyroid hormones?

• A. Decrease basal metabolic rate, heat production, and energy expenditure.
• B. Increase basal metabolic rate, heat production, and energy expenditure.
• C. Increase energy expenditure only.
• D. No change in basal metabolic rate, heat production, or energy expenditure.

Answer: (B)

Thyroid hormones push the body's cells to be more active across the board. By increasing the transcription of enzymes involved in oxidative metabolism and boosting mitochondrial activity, they raise how much oxygen the body uses and how much ATP turnover occurs even at rest. This heightened cellular activity translates into more heat being produced as a byproduct and a higher overall energy expenditure. In brown adipose tissue, thyroid hormones also promote thermogenesis, further boosting heat production. So the change most directly attributed is a rise in basal metabolic rate, heat production, and energy expenditure. The other ideas—decreasing metabolism, or affecting only energy expenditure or none at all—don’t fit the broad, stimulating effects thyroid hormones have on metabolic processes.

Thyroid hormones push the body's cells to be more active across the board. By increasing the transcription of enzymes involved in oxidative metabolism and boosting mitochondrial activity, they raise how much oxygen the body uses and how much ATP turnover occurs even at rest. This heightened cellular activity translates into more heat being produced as a byproduct and a higher overall energy expenditure. In brown adipose tissue, thyroid hormones also promote thermogenesis, further boosting heat production. So the change most directly attributed is a rise in basal metabolic rate, heat production, and energy expenditure. The other ideas—decreasing metabolism, or affecting only energy expenditure or none at all—don’t fit the broad, stimulating effects thyroid hormones have on metabolic processes.