Optometry Admission Test (OAT) 2025 – 400 Free Practice Questions to Pass the Exam

The thyroid gland is primarily responsible for the production of hormones that regulate metabolism, growth, and development. Specifically, it produces two key hormones: thyroxine (T4) and triiodothyronine (T3). These hormones play a critical role in controlling the metabolic rate of the body and influence various physiological processes such as heart rate, body temperature, and the utilization of glucose and fats.

Thyroxine (T4) contains four iodine atoms, while triiodothyronine (T3) contains three. T4 is produced in greater quantities compared to T3 and is converted to T3 in various tissues. T3 is the more active form and has a stronger effect on metabolism. The secretion of these hormones is regulated by the thyroid-stimulating hormone (TSH) from the anterior pituitary gland, which is influenced by the hypothalamus.

The other hormones listed in the other options are not produced by the thyroid gland. Insulin and glucagon are generated by the pancreas and are pivotal in glucose metabolism. Adrenaline (epinephrine) and norepinephrine are catecholamines produced by the adrenal glands and play roles in fight-or-flight responses. Vasopressin (antidiuretic