MEDICAL PHYSIOLOGY

Detailed explanation-1: -The secretion of thyroxine increased temporarily after exposure to the cold. This was shown by a rise in the concentration of thyroxine in the plasma and a simultaneously increased loss of 131I from the thyroid gland.

Detailed explanation-2: -Answer and Explanation: Cooling the body decreases thyroid hormone release, which in turn decreases metabolic and oxygen consumption rate. When the body needs to be cooled thyroid hormone release is inhibited, which results in a decrease in the body’s metabolic rate.

Detailed explanation-3: -The researchers from the Karolinska Institutet in Sweden said that previous studies have attributed this to how thyroid hormone affects the metabolism within cells. The thyroid produces hormones that are able to influence how much the blood vessels dilate. In turn, this affects how much heat can escape the body.

Detailed explanation-4: -Chronic thyroxine treatment led to a 1–2 °C increase in body temperature. This increase was also UCP1-independent and was maintained even at lower ambient temperatures. Thus, it was pyrexia, i.e. a defended increase in body temperature, not hyperthermia.

Detailed explanation-5: -The release of too much thyroxine in the bloodstream is known as thyrotoxicosis. This may be caused by overactivity of the thyroid gland (hyperthyroidism), as in Graves’ disease, inflammation of the thyroid or a benign tumour.