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Connective Tissue General Information • Types and functions: – Loose connective tissue: fat, areolar – insulation, protection – Dense Connective: Ligaments and tendons – binding and support – Cartilage – protection, support – Bone - support – Blood- transportation Common Characteristics • All Connective tissue share the following characteristics, despite the variety. – Develop from the same embryonic tissue – Composed of many different types of cells within the tissue. – Contains extracellular matrix – Great variation in the amount of blood supply (vascularization) Cells in Matrix • Cells in connective tissue make and maintain the ground substance and fibers. • Each type of conn. Tissue have immature and mature forms of these cells. • Immature cells have suffix “-blast” – actively produce matrix. • Mature cells have suffix “-cyte” – maintain health of matrix, reverting to blasts to regenerate matrix after injury. – Fibroblasts – make conn. Tissue/fibers – Chondroblasts – make cartilage, – Osteoblasts – make bone – Hematopoeitic stem cells – make blood Cells in Matrix • Other cells present: – White blood cells (macrophages, plasma cells)– responsible for immune response – Mast cells – responsible for inflammation following injury or infection. Extracellular Matrix • Extracellular matrix is the substance that connective cells are embedded within. • Made of nonliving material called ground substance. – Can be liquid, gel-like, semi-solid or hard. – Texture depends on amount of cell adhesion proteins: proteoglycans which trap water forming a gel. More proteins, more solid ground substance. • Contains fibers that provide great strength, or flexibility, or both. • Extracellular matrix allows Conn. Tissue to bear weight, mechanical abuse – protects!! Dense connective tissue, lots of fibers, little open space. Lots of ground substance – fewer fibers Fibers • Fibers are embedded in ground substance to add strength/flexibility. • Dense fibous (Collagen): stronger than steel of the same size. STRENGTH! Two types: 1. Regularly arranged in tendons,ligament 2. Irregularly arranged: in dermis give elasticity to the skin Dense continued • Dense Irregular – Fibers run in different directions. – Tissue is found where tension is applied in different directions – Example: Dermis of skin Dense Regular Collagen •Ereolar: btw organs,submucosa Fun : connection •Reticular: delicate, forms nets that support free cells. Loose Continued • Reticular – Only contains reticular fibers. – VERY DELICATE – a fine net of fibers. – Supports free blood cells. – Found in lymph nodes, bone marrow,spleen,liver. Reticular Elastic Loose Connective Tissue • Areolar – most widely distributed type. – Serves as “packing material” cushioning organs, subcutaneous, attaches skin to muscle. – Contains all three fibers – Gelatinous – Very loosely packed, lots of liquid – Swells during inflammation (edema) Loose Continued • Adipose = Fat! – Loosely packed with little matrix – Highly cellular : 90% of tissue is adipocytes – Nutrient storage, cushioning. – Richly vascularized – Develops within areolar tissue/subcutaneous • 18% of an average person’s weight • 50% of chubby person Adipose Adipose Dense Regular Dense Irregular Cartilage • Characteristics – Resists tension and pressure – Tough and flexible – No nerves or blood vessels – Lots of collagen and elastic fibers. – 80% water – Chondroblasts make matrix until end of human adolescence. – Mature Chondrocytes found in cavities called lacunae (pit) – Condrotin sulfate give matrix semisolid property Hyaline Cartilage • Looks glassy (hyalin = glass) • Few chondrocytes, all located in lacunae • Mostly matrix – lots of collagen • Reduces friction, absorbs pressure • Covers ends of bones, connects ribs to sternum, forms rings in trachea and bronchi Elastic Cartilage • Looks almost identical to hyaline • Matrix appears more fibrous (chondriocytes) • Many more elastic fibers – makes it very flexible. • Found in nose, ear and epiglottis • Fun: maintain shape, support. Fibrocartilage • Very tough, almost like bone • Consists of rows of chondrocytes and collagen fibers • Withstands great pressure • Found in intervertebral discs. Fibrous Cartilage Bone • Most supportive tissue in body. • Matrix is composed of collagen fibers surrounded by calcium salts. • Osteoblasts make collagen fibers and calcium salts deposited between fibers. • Well vascularized • Osteocytes stored in lacunae • Bone marrow stores fat and makes blood cells. Osteocytes Blood • Atypical connective tissue • Only classified as such because it arises from same embryonic tissue • Blood cells are within a matrix of blood plasma. • Fibers apparent only when blood clots.
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