Connective Tissue: Overview and Characteristics PDF

GENERAL CHARACTERISTICS: connective tissue Letters ✔ ✔ ✔ ✔ Syllabes Words Sentences Cells rarely touch due to “extracellular matrix.” Matrix (fibers & ground substance) is secreted by cells. Consistency varies: liquid, gel or solid. Good nerve & blood supply except in cartilage & tendons. © Co...

GENERAL CHARACTERISTICS: connective tissue Letters ✔ ✔ ✔ ✔ Syllabes Words Sentences Cells rarely touch due to “extracellular matrix.” Matrix (fibers & ground substance) is secreted by cells. Consistency varies: liquid, gel or solid. Good nerve & blood supply except in cartilage & tendons. © Copyright Universidad Europea. Todos los derechos reservados GENERAL CHARACTERISTICS Abundant and widely distributed. Derives from mesoderm. Cells are derived from MESENCHYME (embryonic connective tissue): mesenchymal cells (MSCs) ▪ Immature cells have names that end in –blast (e.g., fibroblast, chondroblast). ▪ Mature cells have names that end in -cyte (e.g., osteocyte). Ectoderm Mesoderm Endoderm -BLAST -CYTE © Copyright Universidad Europea. Todos los derechos reservados GENERAL CHARACTERISTICS FUNCTIONS · Bind, support, repair and strengthen other tissues. · Protect and insulate internal organs. · Compartmentalize structures (muscles). · Transport (blood). · Storage: ▪ Energy reserves (adipose tissue). ▪ Water and electrolytes in extracellular matrix. · Immune response. © Copyright Universidad Europea. Todos los derechos reservados OUTLINE ▪ 2.3 Connective tissue ▪ 2.3.1 General characteristics of connective tissue ▪ 2.3.2 Connective tissue cells ▪2.3.3 Extracellular matrix • Ground substance • Fibres ▪ 2.3.4 Classification of connective tissues • Embryonic • Mature ▪ 2.3.5 Types of connective tissue • Loose connective tissue • Dense connective tissue ▪2.4 Membranes © Copyright Universidad Europea. Todos los derechos reservados COMPONENTS of CONNECTIVE tissue CELLS + EXTRACELLULAR MATRIX RESIDENT TRANSITORY FIBRES -Immature (-blast) -Mature (-cyte) - Leucocytes - Macrophages - Mastocytes - Plasma cells - Collagen - Reticular - Elastic © Copyright Universidad Europea. Todos los derechos reservados GROUND SUBSTANCE - Water - Salts - Proteoglycans Flexible CELLULAR COMPONENTS RESIDENT (non recruited) - Immature (-blast) - Mature (-cyte) © Copyright Universidad Europea. Todos los derechos reservados TRANSITORY -Leucocytes -Macrophages -Mast cells -Plasma cells MESENCHYMAL CELLS • • • Multipotent and undifferentiated. Star-like shape, they differentiate into other cellular types. They normally exist during embryonic stages, but some could last through adulthood. RELEVANCE TO TEETH. Mesenchymal cells form the following differentiated cells: dentin forming odontoblasts, pulp, periodontal ligament. Endometrial mesenchymal cells © Copyright Universidad Europea. Todos los derechos reservados MESENCHYMAL CELLS Some cells into which they differentiate Mesenchymal cell Chondrobla Adipocyt e st Fibroblas t Chondrocyt es © Copyright Universidad Europea. Todos los derechos reservados Mesotheli al Cell Endothelia Osteoblas l t Cell Osteocyt e FIBROBLASTS ▪ Large flat cells with star-like shape. ▪ Principal active cells of connective tissue. They are in various connective tissues. ▪ They produce FIBRES (collagen and elastic fibres) and the GROUND SUBSTANCE Mouse fibroblasts (amorphous gel-like matrix that fills spaces between cells and fibres). Fibrocytes are mature cells that are trapped within the extracellular matrix and maintain the connective tissue. © Copyright Universidad Europea. Todos los derechos reservados Fibroblast MYOFIBROBLASTS ▪ Modified fibroblasts. ▪ Properties between fibroblasts and smooth muscle cells: they secrete collagen and can also contract. ▪ Abundant in healing areas and in the periodontal ligament. ▪ Actively participate in the formation of the root of the teeth. © Copyright Universidad Europea. Todos los derechos reservados ADIPOCYTES ▪ Form adipose tissue and do not divide by mitosis. ▪ Each adipocyte is surrounded by a net of reticular fibres. ▪ They store triglycerides. ▪ We can find them beneath the skin and around internal organs such as heart and kidneys. ▪ Function: protection, energy store, thermoregulation. ▪ Also known as fat cells or lipocytes. © Copyright Universidad Europea. Todos los derechos reservados MORE RESIDENT CELLS • Osteoblasts/ osteocytes • Chondroblasts /chondrocytes © Copyright Universidad Europea. Todos los derechos reservados CELLULAR COMPONENTS TRANSITORY CELLS ORIGIN: pluripotent cells in bone marrow – Macrophages – Plasma cells – Mast cells – Neutrophils – Eosinophils © Copyright Universidad Europea. Todos los derechos reservados CONNECTIVE TISSUE EXTRACELLULAR MATRIX FIBERS GROUND SUBSTANCE Texte - Water - Salts - Proteoglycans © Copyright Universidad Europea. Todos los derechos reservados GROUND SUBSTANCE GOOD AT RESISTING COMPRESSIVE FORCES • Texture: fluid, semifluid, gelatinous or calcified. • Composition: water + salts + proteins + proteoglycans (polysaccharide 95% + protein) – Main polysaccharide: glycosaminoglycans (GAG’s) • Chondroitin sulfate (gelatinous) + • Dermatan sulfate proteins • Keratan sulfate • Hyaluronic acid: dense, viscous, slippery (antiseptic, hydrating) – Adhesion proteins (fibronectins): join collagen fibers with ground substance. © Copyright Universidad Europea. Todos los derechos reservados GROUND SUBSTANCE: GAGs ▪ Capture water, turn the ground surface more jelly-like. • Hyaluronic acid: simplest GAG. viscous substance that brings cells together, maintaining their shape and lubricating them. WBC, sperm and some bacteria make hyaluronidase. Highly negatively charged, inflexible strongly hydrophilic • • • © Copyright Universidad Europea. Todos los derechos reservados Chondroitin sulphate: provides support and adhesiveness to cartilage, bone, skin and blood vessels. Keratan sulphate: bone, cartilage and cornea. Dermatan sulphate: skin, blood vessels, cardiac valves and tendons. GROUND SUBSTANCE: PROTEOGLYCANS Proteoglycan aggregate – glycosamino glycans (GAGs) – hyaluronic acid is thick, viscous and slippery. – adhesion proteins (fibronectin) bind collagen fibers to ground substance. © Copyright Universidad Europea. Todos los derechos reservados Proteoglycan molecule: core FIBRES ▪ GOOD AT RESISTING TENSILE FORCES EXTRACELLULAR MATRIX FIBRES - Collagen - Reticular - Elastic © Copyright Universidad Europea. Todos los derechos reservados Collagen Elastin & fibrillin –Collagen that forms fibres – type I (skin, bones, tendons, ligaments). –Collagen associated to fibrils (types I,II,III, V & IX). –Collagen that forms networks in basal lamina (type IV). –Collagen for anchorage VI (basement membrane: basal lamina binding to epidermis).