#hyperthyroid #GravesDisease #ThyroidHormone MEDICAL ANIMATION TRANSCRIPT: The thyroid is the body's largest endocrine gland and is located anterior and lateral to the trachea and inferior to the larynx. One of the functions of the thyroid is to secrete thyroid hormone, which increases metabolic rate by increasing respiratory rate, increasing heart rate, accelerating breakdown of food for fuel, and increasing heat production. The thyroid hormone interacts with the hypothalamus and pituitary gland in a negative feedback loop to affect metabolic rate. Low levels of thyroid hormone in the blood cause the hypothalamus to release thyrotropin-releasing hormone. Thyrotropin-releasing hormone stimulates the anterior pituitary to release thyroid-stimulating hormone. Thyroid-stimulating hormone stimulates the thyroid gland to secrete thyroid hormones triiodothyronine or T3, and thyroxine or T4, into the bloodstream to affect cells throughout the body. The elevated levels of thyroxine in the blo...