Anatomy and Function

Thyroid Gland

The thyroid is a butterfly-shaped gland in the neck that consists of two lobes and a narrow isthmus between them. It lays over the trachea, or windpipe. The gland makes thyroid hormone, an important regulator of metabolism. Overproduction of thyroid hormone is called hyper thyroidism. Symptoms of hyper thyroidism include nervousness, irritability, heat intolerance, rapid heartbeat, muscle weakness, fatigue, frequent bowel movements, light menstrual periods, weight loss, and hair loss. Under production is called hypothyroidism. Symptoms of hypothyroidism include decreased energy level, feeling cold, muscle pain, slowed thinking, constipation, long menstrual periods, weight gain, brittle nails and hair, and depression.