Final answer:
Thyroid hormone, mainly thyroxine (T4) and triiodothyronine (T3), impacts Basal Metabolic Rate (BMR) by increasing metabolic activity and body heat production, as well as regulating blood glucose levels.
Step-by-step explanation:
Thyroid hormone, specifically thyroxine (T4) and triiodothyronine (T3), is the main determinant of Basal Metabolic Rate (BMR). The effects of thyroid hormone include:
Increase in metabolic activity: Thyroid hormone increases ATP production in cells, which results in increased rates of metabolism. Increase in body heat production: Thyroid hormone's calorigenic effect leads to increased heat production as a byproduct of metabolic reactions. Regulation of blood glucose levels: Thyroid hormone activates genes involved in energy production and glucose oxidation.