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Thyroid hormones play a particularly crucial role in brain maturation during fetal development and first few years of postnatal life [28] The thyroid hormones also play a role in maintaining normal sexual function, sleep, and thought patterns. Increased levels are associated with increased speed of thought generation but decreased focus. [27]
The pituitary gland secretes thyrotropin (TSH; Thyroid Stimulating Hormone) that stimulates the thyroid to secrete thyroxine (T4) and, to a lesser degree, triiodothyronine (T3). The major portion of T3, however, is produced in peripheral organs, e.g. liver , adipose tissue , glia and skeletal muscle by deiodination from circulating T4.
The thyroid system of the thyroid hormones T 3 and T 4 [1] Thyroid hormones are any hormones produced and released by the thyroid gland, namely triiodothyronine (T 3) and thyroxine (T 4). They are tyrosine-based hormones that are primarily responsible for regulation of metabolism. T 3 and T 4 are partially composed of iodine, derived from food. [2]
The hypophyseal portal system is a system of blood vessels in the microcirculation at the base of the brain, connecting the hypothalamus with the anterior pituitary.Its main function is to quickly transport and exchange hormones between the hypothalamus arcuate nucleus and anterior pituitary gland.
Thyroid follicular cells form a simple cuboidal epithelium and are arranged in spherical thyroid follicles surrounding a fluid filled space known as the colloid. The interior space formed by the follicular cells is known as the follicular lumen .
At approximately 24 to 32 days of gestation, the median anlage develops into a bilobed structure. By 50 days of gestation, the medial and lateral anlage have fused together. [6] At 12 weeks of gestation, the fetal thyroid is capable of storing iodine for the production of TRH, TSH, and free thyroid hormone. At 20 weeks, the fetus is able to ...
Parafollicular cells, also called C cells, are neuroendocrine cells in the thyroid. They are called C cells because the primary function of these cells is to secrete calcitonin. [1] They are located adjacent to the thyroid follicles and reside in the connective tissue. These cells are large and have a pale stain compared with the follicular cells.
The hypothalamus secretes thyrotropin-releasing hormone (TRH) into portal veins, which carry this hormone to the anterior pituitary. Thyrotropin-releasing hormone is a relatively small peptide, containing only three amino acids. TRH stimulates the thyrotropic cells through the use of a phospholipase C second messenger system. [1]