Concept explainers
Introduction:
The thyroid gland consists of two lobes, and it is the largest (25 g) adult endocrine gland. The isthmus connects the two lobes of the thyroid gland. It is located at the neck, adjacent to the trachea and beneath the larynx. It appears like a butterfly shape and covered around the trachea. It is composed of thyroid follicles that are covered by follicular cells. The follicular cells secrete thyroid hormones (TH) such as triiodothyronine (T3) and thyroxine (T4). The thyroid gland releases TH into the blood stream. Thyroid hormones act by binding to their thyroid hormone receptors (TR), which is a superfamily of nuclear receptors. TR-encoding genes are classified into α (TRα) and β (TRβ). Thyroid-stimulating hormone (TSH) regulates hormones (T3 and T4) secretion from the thyroid. TH raises the
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Anatomy & Physiology: The Unity of Form and Function
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- Biology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStax