正常人体的组织结构及其功能（The structure and function of normal human body）

正常人体的组织结构及其功能（The structure and function of normal human body） 正常人体的组织结构及其功能(The structure and function of normal human body) The second chapter is about the structure and function of normal human body 1. Epithelial tissue defined by large numbers of closely arranged, well structured epithelial cells and a very small amount of extracellular matrix. The general characteristics of epithelial tissue: large amounts of cells and a small amount of extracellular matrix; polarity; no blood vessels; abundant nerve endings. The distribution and function of epithelial tissue: 1, distribution: distributed in the body surface, tube, cavity, bladder organs, the surface of the cavity, the surface of certain organs, glands and so on. 2: function: protection, absorption, secretion, excretion, sensory and other functions. Epithelial tissue classification: covering epithelium, glandular epithelium and sensory epithelium 2. The classification of covering epithelium: single layer squamous epithelium surface: irregular or polygonal cells, oval nucleus, located in the middle of cell, jagged edge of cell border, mosaic each other. Vertical cell: flat and thin, less quality, protruding into the nuclear. Endothelium: a single layer of squamous epithelium distributed in the heart, blood vessels, and lymphatics. Mesothelial: a single layer of squamous epithelium distributed in the pleura, peritoneum, and the heart envelope. The main function is to keep the organs surface smooth, conducive to exchange of substances and liquid flow, and facilitate internal organ activities. Single cuboidal epithelium surface: each cell is hexagonal or polygonal; vertical section: cubic shape, nuclear ellipse, located in the center. Located in the thyroid and renal tubules, it has the function of absorption and secretion. Single columnar columnar epithelium surface: polygonal vertical view: the cells are columnar, oval, and near the base of cells. The distribution in the stomach, gall bladder and uterus etc. the functions of absorption and secretion of the pseudostratified ciliated columnar epithelium in the respiratory tract mucosa composed of columnar cells, spindle cells, pyramidal cells and goblet cells, columnar cells of the free surface of a large number of cilia. The stratified squamous epithelium of skin surface epithelial cells without nuclei, abundant keratin, called keratinized stratified squamous epithelium in the oral cavity, esophagus and vaginal distribution of shallow cell nucleus, keratin, called non keratinized stratified squamous epithelium and the transitional epithelium in the bladder and urination pipe features the changes of cell shape and layers with organ changes. 3, the special structure of epithelial tissue: epithelial cell free surface 1, microvilli: microvilli are cell membranes and cytoplasm common to the cavity surface protruding. 2. Cilia: cilia are the longer processes projecting from the free surface of epithelial cells and have the ability of rhythmic oscillation. Two, epithelial thin side 1, tight junction function: to enhance the close combination between cells, sealing the free surface between cells, to prevent the leakage of nutrients between cells. 2, the middle junction is located in the deep part of the tight junction, showing a continuous band around the epithelial tissue. Function: maintain cell shape and transfer cell contraction force; and adhesion. 3, bridge is located in the middle of deep connection, waspatchy, ranging in size. The most solid cell connection. 4, the gap junction function: porphyritic cells can borrow ion gap junctions to each other for some small molecule chemical information exchange, transfer. Moreover, the secondary resistance is very low, which is beneficial to the transmission of point impulse between cells. Cell junctions are not only distributed in epithelial cells, but also in muscle tissue, nerve tissue and nerve tissue cells. Four kinds of cell connections, if there are two kinds of connections at the same time, called junctional complex. Three epithelial cell base 1, basement membrane: epithelial tissue and deep connective tissue between the layer of film. Support, connection and fixation effect on epithelial cells, is also a semipermeable membrane, with selective permeability, is conducive to the epithelium and deep connective tissue material exchange. 2 plasma membrane folds enlarge the basal surface area of epithelial cells and facilitate ion and water transport. 3, the half bridge structure is half of the desmosomes, which is beneficial for epithelial cells adhering to the basement membrane. 4. Glandular epithelium: the epithelium with secretory function is called glandular epithelium. Gland: an organ composed of glandular epithelium and a gland. Exocrine glands are usually composed of two parts: the secretory portion and the duct. The secretory portion is mainly composed of glandular cells and has secretory function. The duct is an epithelial conduit that connects directly to the secretory portion, and is a route to exclude secretions. According to the nature of gland cell secretion, it can be divided into serous gland, mucous gland and mixed gland. 5, connective tissue, connective tissue characteristics: (1) less cells, many kinds of; cells, stroma, fiber and fiber. The cell dispersion is distributed in the intercellular stroma, without polarity. It is rich in blood vessels, nerves and lymph vessels. Mesenchyme derived from embryonic mesoderm. It has the functions of support, connection, nutrition, protection, rehabilitation and defense. Two. The classification of connective tissue: 1, the intrinsic connective tissue (extracellular matrix is colloidal): loose connective tissue, dense connective tissue, reticular connective tissue, adipose tissue. Vegetative tissue (the extracellular matrix is liquid): blood and lymph. 6. The connective tissue, a loose connective tissue, is a soft, elastic, ductile and widely distributed tissue. There are three kinds of substances: cell, stroma and fiber. 1. Matrix: it is a kind of homogeneous, translucent and amorphous gum like substance. Tissue fluid: constantly circulating and renewing, supplying cells, tissues, nutrients and oxygen, and discharging their metabolites and carbon dioxide. Tissue fluid is an important medium for the exchange of substances between the blood and cells. 2, three: 1 collagen fiber: most. HE pink broadband, interwoven into a net. When fresh, it is white, also called white fiber. The chemical component is collagen. Having tenacity or lack of elasticity. The elastic fibers: HE not easy coloring, fiber is fine, disorder, often branch. Yellow when it is fresh, also called yellow fiber. The chemical component is elastin. Good elasticity. The reticular fibers: thin, branched, woven into the net. HE is not obvious, silver combustion is black, called silver fiber. The chemical composition and properties are the same as those of silver fibers. 3: cells: a small number of species. Fibroblasts, macrophages, plasma cells, mast cells, adipocytes, undifferentiated mesenchymal cells, blood cells and so on. The fibroblast structure flat and irregular shape, protruding, side view fusiform, located beside the collagen fiber. HE staining is shallow and unclear; the nucleus is oval and pale; the nucleolus is 1~2; there are abundant rough endoplasmic reticulum, free ribosome and developed Golgi complex in cytoplasm. Three fibers and matrix are mainly generated. The macrophages are widely distributed, large number of. Contains a large number of lysosomes and macrophages. It has phagocytosis and immune defense function. Results: plasma cells derived from B cells, synthesis and secretion of immunoglobulin antibody. The mast cells: round or oval, nuclear small and round. Full of large amounts of special particles. The particles contain heparin, histamine, leukotrienes and eosinophils, chemokines, etc.. Heparin - anticoagulant, histamine, and leukotriene - causes vasodilation, increased permeability, smooth muscle contractions, and allergic reactions. Eosinophils, chemotactic factors - attract eosinophils and reduce allergic reactions.