Health Encyclopedia


Document Search by P00432

Thyroid GlandGlándula Tiroides

The Thyroid Gland

Anatomy of the thyroid gland

Illustration of the thyroid glad and its location
Thyroid Gland - Click to Enlarge

The thyroid gland is located in the front of the neck (just above the breastbone and below the Adam's apple). The small, two-inch gland consists of two lobes, one on each side of the windpipe, connected by a small bridge of thyroid tissue called the isthmus.

The thyroid tissue is made up of two types of cells: follicular cells and parafollicular cells. Most of the thyroid tissue consists of the follicular cells, which secrete the iodine-containing thyroid hormones. They consist of thyroxine (T4) and triiodothyronine (T3). The parafollicular cells (also called C cells) secrete the hormone calcitonin. Calcitonin is a weak hormone that helps in the regulation of calcium. When the thyroid is completely removed because of cancer or disease, the removal of these C cells produces no problems with calcium regulation. The follicular cells require an adequate supply of iodine in order to produce the thyroid hormones.

Functions of the thyroid gland

The thyroid plays an important role in regulating the body's metabolism. Virtually every tissue in the body is affected or regulated by thyroid hormone. It regulates our metabolism, brain development and function, skin, hair, eyes, heart, and intestine function. The thyroid hormones enter into tissues and regulate how those tissues produce or do not produce certain proteins. The thyroid function is controlled by the “Master Gland” in the pituitary within the brain. The pituitary is controlled by a region in the brain called the hypothalamus. The calcitonin hormone works together with the parathyroid hormone to regulate calcium levels in the body.

Related Items
Drug Reference
  Sodium Iodide I-131
  Thyroid Quiz
Daily News Feed
  Chemicals in Carpets, Cosmetics Tied to Thyroid Problems
  Childhood Abuse Linked to Later Thyroid Problems for Women
  Underactive Thyroid Not Linked to Memory Problems
  Could Thyroid Activity Raise Depression Risk in Seniors?
  Study Examines Effort to Preserve Voice During Thyroid Surgery
  Iodine Deficiency Common in Pregnancy, Pediatricians Warn
  Thyroid Problem Can Lead to Sick Leaves From Work, Study Finds