What is the primary function of thyroxine (T3 and T4)?

The primary function of thyroxine (T3 and T4) is to stimulate metabolic rate. These hormones, produced by the thyroid gland, play a crucial role in regulating how the body uses energy. They influence the speed of biochemical reactions, impacting metabolism, which encompasses all the processes by which the body converts food into energy.

Thyroxine increases the basal metabolic rate, meaning that it accelerates the rate at which the body burns calories and generates heat. This stimulation of metabolism is essential for maintaining various bodily functions, including growth, development, and overall energy expenditure. Adequate levels of T3 and T4 are vital for normal physiological activities, as they help ensure that the body's energy needs are met efficiently.

In contrast, the other options do not accurately represent the primary function of thyroxine. While hormones can influence these processes to some extent, they are not the main actions of T3 and T4.