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  • Topic: Thyroid, Iodine, Thyroid hormone
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From Wikipedia, the free encyclopedia

|thyroid | |[pic] | |Thyroid and parathyroid. | |Latin |glandula thyroidea | |Gray's |subject #272 1269 | |System |Endocrine system | |Precursor |Thyroid diverticulum (an extension of endoderm into | | |2ndBranchial arch) | |MeSH |Thyroid+Gland | |Dorlands/Elsevier |Thyroid gland |

The thyroid gland or simply, the thyroid /ˈθaɪərɔɪd/, in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage(which forms the laryngeal prominence, or "Adam's apple"). The isthmus (the bridge between the two lobes of the thyroid) is located inferior to the cricoid cartilage.

The thyroid gland controls how quickly the body uses energy, makes proteins, and controls how sensitive the body is to other hormones. It participates in these processes by producing thyroid hormones, the principal ones being triiodothyronine (T3) and thyroxine which can sometimes be referred to as tetraiodothyronine (T4). These hormones regulate the rate of metabolism and affect the growth and rate of function of many other systems in the body. T3and T4 are synthesized from both iodine and tyrosine. The thyroid also produces calcitonin, which plays a role in calcium homeostasis.

Hormonal output from the thyroid is regulated by thyroid-stimulating hormone (TSH) produced by the anterior pituitary, which itself is regulated by thyrotropin-releasing hormone (TRH) produced by the hypothalamus.

The thyroid gets its name from the Greek word for "shield", due to the shape of the related thyroid cartilage. The most common problems of the thyroid gland consist of an overactive thyroid gland, referred to as hyperthyroidism, and an underactive thyroid gland, referred to ashypothyroidism.

|Contents | |  [hide]  | |1 Anatomy | |1.1 Embryological development | |1.2 Histology | |2 Physiology | |2.1 T3 and T4 production and action | |2.2 T3 and T4 regulation | |3 Disorders | |3.1 Hyperthyroidism | |3.2 Hypothyroidism | |3.3 Initial hyperthyroidism followed by hypothyroidism | |3.4 Cancers | |3.5 Non-cancerous nodules | |3.6 Congenital anomalies | |3.7 Other disorders | |3.8 Thyroid function tests | |3.9 Significance of iodine | |4 History | |5 Other animals...