|
Thyroid Follicle
Thyroid follicular cells (also called thyroid epithelial cells or thyrocytes) are the major cell type in the thyroid gland, and are responsible for the production and secretion of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). They form the single layer of cuboidal epithelium that makes up the outer structure of the almost spherical thyroid follicle. Structure Location 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. The basolateral membrane of follicular cells contains thyrotropin receptors which bind to thyroid-stimulating hormone (TSH) found circulating in the blood. Calcitonin-producing parafollicular cells are also found along the basement membrane of the thyroid follicle, interspersed between follicular cells; and in spaces between the spherical follicles. Pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endocrine System
The endocrine system is a messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant Organ (biology), organs. In vertebrates, the hypothalamus is the neural control center for all endocrine systems. In humans, the major endocrine glands are the thyroid gland, thyroid, parathyroid gland, parathyroid, pituitary gland, pituitary, pineal gland, pineal, and adrenal glands, and the (male) testis and (female) ovaries. The hypothalamus, pancreas, and thymus also function as endocrine glands, among other functions. (The hypothalamus and pituitary glands are organs of the Neuroendocrinology#Neuroendocrine system, neuroendocrine system. One of the most important functions of the hypothalamusit is located in the brain adjacent to the pituitary glandis to link the endocrine system to the nervous system via the pituitary gland.) Other organs, such as the kidneys, also have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 appear in the genetic code of life. Amino acids can be classified according to the locations of the core structural functional groups ( alpha- , beta- , gamma- amino acids, etc.); other categories relate to polarity, ionization, and side-chain group type ( aliphatic, acyclic, aromatic, polar, etc.). In the form of proteins, amino-acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling life on Earth and its emergence. Amino acids are formally named by the IUPAC- IUBMB Joint Commi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endocrine Cells
The endocrine system is a messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant organs. In vertebrates, the hypothalamus is the neural control center for all endocrine systems. In humans, the major endocrine glands are the thyroid, parathyroid, pituitary, pineal, and adrenal glands, and the (male) testis and (female) ovaries. The hypothalamus, pancreas, and thymus also function as endocrine glands, among other functions. (The hypothalamus and pituitary glands are organs of the neuroendocrine system. One of the most important functions of the hypothalamusit is located in the brain adjacent to the pituitary glandis to link the endocrine system to the nervous system via the pituitary gland.) Other organs, such as the kidneys, also have roles within the endocrine system by secreting certain hormones. The study of the endocrine system and its disorders ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Distinct Cell Types In The Adult Human Body
The list of human cell types provides an enumeration and description of the various specialized cells found within the human body, highlighting their distinct functions, characteristics, and contributions to overall physiological processes. Cells may be classified by their physiological function, histology (microscopic anatomy), lineage, or gene expression. Total number of cells The adult human body is estimated to contain about 30 trillion (3×1013) human cells, with the number varying between 20 and 100 trillion depending on factors such as sex, age, and weight. Additionally, there are approximately an equal number of bacterial cells. The exact count of human cells has not yet been empirically measured in its entirety and is estimated using different approaches based on smaller samples of empirical observation. It is generally assumed that these cells share features with each other and thus may be organized as belonging to a smaller number of types. Classification ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Human Cell Types Derived From The Germ Layers
This is a list of Cell (biology), cells in humans derived from the three embryonic germ layers – ectoderm, mesoderm, and endoderm. Cells derived from ectoderm Surface ectoderm Skin * Trichocyte (human), Trichocyte * Keratinocyte Anterior pituitary * Gonadotropic cell, Gonadotrope * Corticotropic cell, Corticotrope * Thyrotropic cell, Thyrotrope * Somatotropic cell, Somatotrope * Prolactin cell, Lactotroph Tooth enamel * Ameloblast Neural crest Peripheral nervous system * Neuron * Neuroglia, Glia ** Schwann cell ** Satellite glial cell Neuroendocrine system * Chromaffin cell * Glomus cell Skin * Melanocyte ** Nevus cell * Merkel cell Teeth * Odontoblast * Cementoblast Eyes * Corneal keratocyte Smooth muscle Neural tube Central nervous system * Neuron * Glia ** Astrocyte ** Ependyma, Ependymocytes ** Müller glia (retina) ** Oligodendrocyte ** Oligodendrocyte progenitor cell ** Pituicyte (posterior pituitary) Pineal gland * Pinealocyte Cells derived from mesoderm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyroid Diverticulum
The thyroid pouch or thyroid diverticulum is the embryological structure of the second pharyngeal arch from which thyroid follicular cells derive. It grows from the floor of the pharynx. See also * Diverticulum In medicine or biology, a diverticulum is an outpouching of a hollow (or a fluid-filled) structure in the body. Depending upon which layers of the structure are involved, diverticula are described as being either true or false. In medicine, t ... References Human head and neck Embryology Thyroid {{developmental-biology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pendrin
Pendrin is an Anion-exchange, anion exchange protein that in humans is encoded by the ''SLC26A4'' gene (solute carrier family 26, member 4). Pendrin was initially identified as a sodium-independent chloride-iodide exchanger with subsequent studies showing that it also accepts formate and bicarbonate as substrates. Pendrin is similar to the Band 3 transport protein found in red blood cells. Pendrin is the protein which is mutated in Pendred syndrome, which is an autosomal recessive disorder characterized by sensorineural hearing loss, Goitre, goiter and a partial organification problem detectable by a positive perchlorate test. Pendrin orthologs are responsible for mediating the electroneutral exchange of chloride (Cl−) for bicarbonate (HCO3−) across a plasma membrane in the chloride cells of freshwater fish, and show changes in expression in response to salinity change in the gills of Atlantic stingrays. By phylogenetic analysis, pendrin has been found to be a close relative ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium-iodide Symporter
The sodium/iodide cotransporter, also known as the sodium/iodide symporter (NIS), is a protein that in humans is encoded by the ''SLC5A5'' gene. It is a transmembrane glycoprotein with a molecular weight of 87 kAtomic mass unit, Da and 13 transmembrane domains, which transports two sodium cations (Na+) for each iodide anion (I−) into the cell. NIS mediated uptake of iodide into Thyroid epithelial cell, follicular cells of the thyroid gland is the first step in the synthesis of thyroid hormone. Iodine uptake Iodine uptake mediated by thyroid Thyroid epithelial cell, follicular cells from the blood plasma is the first step for the synthesis of thyroid hormones. This ingested iodine is bound to serum proteins, especially to albumins. The rest of the iodine which remains unlinked and free in bloodstream, is removed from the body through urine (the kidney is essential in the removal of iodine from extracellular space). Iodine uptake is a result of an active transport mechanism media ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodine
Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a violet gas at . The element was discovered by the French chemist Bernard Courtois in 1811 and was named two years later by Joseph Louis Gay-Lussac, after the Ancient Greek , meaning 'violet'. Iodine occurs in many oxidation states, including iodide (I−), iodate (), and the various periodate anions. As the heaviest essential mineral nutrient, iodine is required for the synthesis of thyroid hormones. Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities. The dominant producers of iodine today are Chile and Japan. Due to its high atomic number and ease of attachment to organic compounds, it has also found favour as a non-toxic radiocontrast material. Because of the spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protease
A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalysis, catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do this by cleaving the peptide bonds within proteins by hydrolysis, a reaction where water breaks Covalent bond, bonds. Proteases are involved in numerous biological pathways, including Digestion#Protein digestion, digestion of ingested proteins, protein catabolism (breakdown of old proteins), and cell signaling. In the absence of functional accelerants, proteolysis would be very slow, taking hundreds of years. Proteases can be found in all forms of life and viruses. They have independently convergent evolution, evolved multiple times, and different classes of protease can perform the same reaction by completely different catalytic mechanisms. Classification Based on catalytic residue Proteases can be classified into seven broad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endocytosis
Endocytosis is a cellular process in which Chemical substance, substances are brought into the cell. The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form a Vesicle (biology and chemistry), vesicle containing the ingested materials. Endocytosis includes pinocytosis (cell drinking) and phagocytosis (cell eating). It is a form of active transport. History The term was proposed by Christian de Duve, De Duve in 1963. Phagocytosis was discovered by Élie Metchnikoff in 1882. Pathways Endocytosis pathways can be subdivided into four categories: namely, receptor-mediated endocytosis (also known as clathrin-mediated endocytosis), caveolae, pinocytosis, and phagocytosis. * Clathrin-mediated endocytosis is mediated by the production of small (approx. 100 nm in diameter) vesicles that have a morphologically characteristic coat made up of the cytosolic protein clathrin. Clathrin-coated vesicles (CCVs) are found in vir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyroperoxidase
Thyroid peroxidase, also called thyroperoxidase (TPO), thyroid specific peroxidase or iodide peroxidase, is an enzyme expressed mainly in the thyroid where it is secreted into colloid. Thyroid peroxidase oxidizes iodide ions to form iodine atoms for addition onto tyrosine residues on thyroglobulin for the production of thyroxine (T4) or triiodothyronine (T3), the thyroid hormones. In humans, thyroperoxidase is encoded by the ''TPO'' gene. Function Inorganic iodine enters the body primarily as iodide, I−. After entering the thyroid follicle (or thyroid follicular cell) via a Na+/I− symporter (NIS) on the basolateral side, iodide is shuttled across the apical membrane into the colloid via pendrin after which thyroid peroxidase oxidizes iodide to atomic iodine (I) or iodinium (I+). The chemical reactions catalyzed by thyroid peroxidase occur on the outer apical membrane surface and are mediated by hydrogen peroxide. The "organification of iodine", the incorporation of iodi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
