Secretory tissue

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CONCEPT OF SECRETION: synthesis by cells of certain specific substances that then are released to internal or external environment of the organism to pursue their claims. The phenomena of secretion are carried out by epithelial cells that form glandular epithelia. There, a non epithelial cells that synthesize and release the interstitial extracellular matrix, histamine or antibodies. Other produce materials for their own use. Those would also be secretory organs, such as the gonads, bone marrow and lymphoid producers whose own cells are released. STRUCTURE OF secretory cell structure varies according to the functional time, the morphology is generally polygonal with membrane differentiations: devices of union and communication and outgrowths / invaginations that determine the entry or exit of materials. The grouping of these cells arise glands. Secretory cycle: phase: resting functional for incorporation of precursors, synthesis, storage and disposal. MECHANISMS OF RELEASE OF THE SECRETION: * Merocrino: the product is released by fusion of the membrane that wraps the plasma, is the most common. * Apocrine: With the secretion of the material is poured cytoplasmic it is as if the cell undergoes a "decapitation". * Halocrino: the cell is removed completely, usually breaks, leaving the contents outside. Secreting cells TYPES: 1.Segun the secreted product: 1a) cells proteins and biogenic amines: Structure: highly developed RER, free polyribosomes, Golgi near the nucleus. Basophils secretion granules and electron dense. Examples: pancreas exocrine and endocrine cells of the adrenal medulla and paraganglia cells, ACTH and STH of the pituitary ... 1b) of glycoproteins: Structure: moderately developed RER, Golgi very clear; secretion granules PAS positive and more or less electron dense. Examples: Calciform cells, mucous cells of salivary glands, cells of the superficial lining of the stomach and the endocervix ... 1.c) steroid: Structure: numerous mitochondria, some tubular cristae; REL highly developed; lipid vesicles aspect; clumps of lipofuscin. To demonstrate its content requires frozen sections and special stains for lipids. Examples: endocrine cells of the adrenal cortex, ovaries and testes. 1.d) of special products: HCl, milk, sweat, tears, of wax, tallow. 2.Segun the fate of the secretion: 2a) Exocrine: They shed their products: "Outside the agency, other agencies-A,-a natural cavities. 2.b) Endocrine: They shed their secretion directly into the blood and occasionally , the cerebrospinal fluid. Target cell signaling are distant, so that the hormone has the blood of vehicles. 2.c) Paracrine: They pour their products to the immediate surroundings without a duct system. Examples: cells producing local chemical mediators, growth factors, cytokines ... 2.d) Autocrine: The cell signaling is his own target, so as to stimulate herself. Example: tumor cells. BIOGENESIS AND GENERAL ORGANIZATION OF THE exocrine and endocrine glands:Secretory epithelial cells forming glands are arranged, which can be uni-or multicellular and available in surface or deep, forming a complete organ or part of an organ. They originate from embryonic epithelia lining following different paths, "The differential secretory cells remain on the surface, aligned or dispersed between the coating. "There is a way of growing epithelial ingrowth into surrounding tissues, in this case can occur: * to retain the link with the outside * the connection disappears. Exocrine Glands: 1.Celulas grouped and arranged on the surface: * meet coating and secretion functions. Example: surface epithelium of the stomach and endocervix. 2.Celulas scattered and arranged on the surface: These are unicellular glands. Example: Calciform cells and pneumocytes type 2. 3.Celulas grouped and arranged in depth: * Serving = secretory acinus or Adenomera: tubular, alveolar, acinar. Acinus The term usually refers to a group of exocrine cells which discharge their secretion into the middle light that they enclose. According to the released product speaks of serous acini, mucous seromucous and otherwise. * Serving = excretory duct system, simple, branched, coiled. * = Connective tissue stroma that surround the capsule form and the partitions between lobes and lobules Parenchymal Endocrine Gland: Structure general polygonal cells of epithelial appearance, that when grouped together

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