What role does thyroxin play in the body, and how does it influence metabolic rate and body temperature?

Sourav PanNovember 9, 2024

Answered

Thyroxine, also known as T4, is a crucial hormone produced by the thyroid gland that plays a significant role in regulating various physiological processes in the body, particularly metabolic rate and body temperature.

Role of Thyroxine in the Body

1. Regulation of Metabolic Rate:
   • Thyroxine is essential for establishing the basal metabolic rate (BMR), which is the rate at which the body expends energy at rest. It influences how many calories are burned by stimulating metabolic processes such as carbohydrate and lipid metabolism. T4 promotes the oxidation of glucose and fatty acids, thereby increasing energy expenditure and metabolic activity across nearly all organ systems.
2. Influence on Energy Expenditure:
   • By regulating various metabolic pathways, thyroxine enhances the utilization of ATP and promotes processes such as lipolysis (breakdown of fats) and gluconeogenesis (production of glucose from non-carbohydrate sources). This results in increased energy expenditure and contributes to maintaining overall energy balance in the body.
3. Impact on Thermogenesis:
   • An important consequence of increased metabolic activity due to thyroxine is the production of heat, which plays a vital role in regulating body temperature. Thyroxine stimulates thermogenesis, which is the process of heat production in organisms. It does this by increasing mitochondrial respiration and enhancing the activity of sodium-potassium ATPase pumps, leading to greater heat generation as a byproduct of metabolic processes .

Influence on Body Temperature

1. Thermoregulation:
   • Thyroxine helps regulate body temperature by influencing how much heat is produced through metabolism. When body temperature decreases, thyroxine secretion increases to stimulate heat production, thereby helping to maintain homeostasis . Conversely, an excess of thyroxine (as seen in hyperthyroidism) can lead to elevated body temperature due to increased metabolic rates.
2. Effect on Blood Vessels:
   • Research indicates that thyroxine affects blood vessel dilation, which can influence heat dissipation from the body. This means that thyroxine not only helps generate heat but also regulates how much heat can escape from the body through adjustments in blood flow .
3. Sensitivity to Temperature Changes:
   • Individuals with thyroid disorders often exhibit altered sensitivity to environmental temperatures; for instance, those with hypothyroidism may feel cold due to reduced metabolic activity and lower heat production