A member of our endocrine system, the thyroid gland produces hormones that help control many of our body functions, such as weight and temperature. Located at the base of our neck, this butterfly-shaped gland makes several hormones, which are collectively known as thyroid hormones. These hormones are especially key in the brain development of infants and children. Thyroxine, also known as T4, is the primary hormone secreted by the thyroid gland; this hormone helps control our metabolism, a chemical process that turns our food into energy. A lack of iodine in your food can cause the thyroid to swell, a condition called a goiter. Several other disorders and diseases can affect this gland, including cancer. If you notice swelling in your neck or feel a lump, make sure you see your doctor; this could indicate a problem with this important gland.