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Parathyroid hormone (PTH)

/parəˈθʌɪrɔɪd/ /ˈhɔːməʊn/ Noun Also called parathormone or parathyrin. 1. Secreted by the chief cells of the parathyroid glands as a polypeptide containing 84 amino acids. It acts to increase the concentration of calcium (Ca2+) in the blood, whereas calcitonin (a hormone produced by the parafollicular cells (C cells) of the thyroid gland) acts to decrease calcium concentration. PTH acts to increase the concentration of calcium in the blood by acting upon the parathyroid hormone 1 receptor (high levels in bone and kidney) and the parathyroid hormone 2 receptor (high levels in the central nervous system, pancreas, testis, and placenta). PTH half-life is approximately 4 minutes. It has a molecular mass of 9.4 kDa. ( 2. A polypeptide hormone that is released by the chief cells of the parathyroid glands and is involved in raising the levels of calcium ions in the blood. ( 3. Hormone synthesized and released into the blood stream by the parathyroid glands; regulates phosphorus and calcium in the body and functions in neuromuscular excitation and blood clotting....

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/pəˈrɛŋkɪmə/ Noun 1. The essential and distinctive tissue of an organ or an abnormal growth as distinguished from its supportive framework. ( 2. Animal tissue that constitutes the essential part of an organ as contrasted with e.g. connective tissue and blood vessels. ( 3. The primary tissue of higher plants composed of thin-walled cells that remain capable of cell division even when mature; constitutes the greater part of leaves, roots, the pulp of fruits, and the pith of stems. ( 4. In plants, tissue typically composed of living cells that are thin-walled, unspecialized in structure, and therefore adaptable, with differentiation, to various functions. Parenchyma may be compact or have extensive spaces between the cells. It is often called ground, or fundamental, tissue and makes up the mesophyll (internal layers) of leaves and the cortex (outer layers) and pith (innermost layers) of stems and roots; it also forms the soft tissues of fruits. ( Word origin: From Greek parenkhyma “something poured in beside,” from para– “beside” + enkhyma “infusion,” from en– “in” + khein “to...

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/pəˈriːsɪs,ˈparɪsɪs/ Noun 1. A condition typified by a weakness of voluntary movement, or partial loss of voluntary movement or by impaired movement. When used without qualifiers, it usually refers to the limbs, but it can also be used to describe the muscles of the eyes (ophthalmoparesis), the stomach (gastroparesis), and also the vocal cords (Vocal cord paresis). Neurologists use the term paresis to describe weakness, and plegia to describe paralysis in which all voluntary movement is lost. ( 2. A condition of muscular weakness caused by nerve damage or disease; partial paralysis. (Google Dictionary) 3. Slight or partial paralysis ( Word origin: Modern Latin, from Greek paresis “letting go, slackening of strength, paralysis,” from stem of parienai “to let go,” from para– + hienai “to send,...

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/pəˈrʌɪɪt(ə)l/ Noun 1. A parietal structure. (Google Dictionary) 2. (Anatomy) Either of the two parietal bones, on the top and side of the skull. ( Adjective 1. Relating to or denoting the wall of the body or of a body cavity or hollow structure. (Google Dictionary) 2. Of or relating to the parietal bones. ( 3. (Botany) Borne on the inside of the ovary wall. Used of the ovules or placentas in flowering plants. ( Word origin: From Late Latin parietalis “of walls,” from Latin paries (genitive parietis) “wall” (of a building), of unknown origin. In U.S. also “pertaining to the residents and rules of a college or...

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