2 Connective Tissue Functions Binding and support Protection Insulation Transportation
3 Connective Tissue - Characteristics Common OriginAll arise from the mesenchyme (embryonic tissue)Degrees of vascularitySupply of blood vessels – vascularized to poorly vascularized.Extracellular matrixAll other tissues are composed of cells. CT is composed mainly of the nonliving extracellular matrix which separates the living cells of the tissue. This allows it to bear weight, withstand tension, physical trauma, etc.
4 Connective Tissue Structural elements Ground Substance (matrix) Fibers (matrix)Cells
5 Connective Tissue Ground Substance Fills the space between the cells and contains the fibers.Composed:Interstitial fluidCell adhesion proteinsGlue to allow cells to attach themselves to matrix elementsProteoglycansGlycosaminoglycans (GAGs) attach and trap water to form anything from a fluid to a viscous gel – more GAGs, more viscous.
6 Connective Tissue - Fibers Provide supportTypes of fibersCollagen fibers“white fibers” has a white appearanceVery strong stronger than steel fibers!Found in tendons and ligamentsElastic fibers“yellow fibers” has a yellow appearanceAble to stretch (protein elastin) – allows tissue to return to normal length and shapeReticular fibersShort, fine, collagenous fibers and are continuous with collagen fibers.Reticul networkOften seen where connective tissue connects with other tissues forms a fuzzy “net” that allows more “give”
7 Connective Tissue - Cells Each major class of c.t. has a fundamental cell.Undifferentiated cells, indicated by –blast (“bud” “forming”)Fibroblast – Connective tissue properChondroblast – CartilageOsteoblast – BoneHematopoietic stem cell - BloodActively mitotic cells!!
8 Connective Tissue - Cells Once the –blast cells synthesize the matrix, they assume their less active, mature mode, indicated by –cyte (fibrocyte, osteocyte….)These cells maintain the health of the matrix!If matrix is injured can revert back to –blast.
9 Connective Tissue - Cells Other cells found within C.T.White blood cells – defensive (neutrophils, eosinophils, lymphocytes)Plasma cells – produces antibodiesMast cells – oval, typically cluster along blood vessel walls. Detect foreign substances and initiate inflammatory responseMacrophages – large, irregularly shaped cells that phagocytize foreign materials. Found throughout loose C.T., bone marrow, and lymphatic tissue.
10 Connective Tissue Most abundant and widely distributed tissue Four main classes:Connective tissue properLoose Connective TissuesAreolar, adipose, and reticularDense Connective TissuesDense regular, dense irregular, elasticCartilageHyaline, elastic, fibrousBone TissueBlood
11 Connective Tissue Areolar DescriptionGel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells and some wbc’sFunctionWraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid.LocationWidely distributed under epithelia of body.
12 Connective Tissue Adipose DescriptionFat!!Accounts for about 18% of body weightFunctionProvides reserve food fuel; insulates against heat loss; supports and protects organsLocationUnder skin; around kidneys and eyeballs; within abdomen; in breasts
13 Connective Tissue Reticular DescriptionNetwork of reticular fibers in a typical loose ground substance; reticular cells lie on the network.FunctionFibers from a soft internal skeleton (stroma) that supports other cell types including wbc’s, mast cells, and macrophages.LocationLymphoid organs (lymph nodes, bone marrow, and spleen).
14 Connective Tissue Dense Regular DescriptionClosely packed collagen fibers all running in the same directionPoorly vascularizedFunctionAttaches muscles to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one directionLocationTendons and ligaments
15 Connective Tissue Dense Irregular DescriptionThick collagen fibers that run in all directionsFunctionAble to withstand tension exerted in many directions; provides structural strengthLocationDermis of the skin; submucosa of digestive tract; fibrous capsules of organs and of joints
16 Connective Tissue Hyaline Cartilage DescriptionGristleMost commonAmorphous but firm matrix; collagen fibers from and imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae
17 Connective Tissue Hyaline Cartilage FunctionSupports and reinforces; has resilient cushioning properties; resists compressive stressLocationForms most of the embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea and larynx
18 Connective Tissue Elastic Cartilage DescriptionSimilar to hyaline cartilage, but more elastic fibers in the matrixFunctionMaintains the shape of a structure while allowing great flexibilityLocationEar, tip of nose, epiglottis
19 Connective Tissue Fibrocartilage DescriptionFound in areas of high stressMatrix similar to but less firm that hyaline; thick collagen fibers predominateAvascularFunctionTensile strength with the ability to absorb compressive shock, prevents bone-to-bone contact, shock absorberLocationSpinal discs, pads within knee joint
20 Connective Tissue Bone DescriptionHard, calcified matrix contain many collagen fibers; osteocytes lie in lacunaeHighly vascularizedFunctionSupports and protects; levers for the muscles; stores calcium and other minerals and fat; marrow on inside make blood cellsLocationBone
21 Connective Tissue Blood DescriptionRed and white blood cells in a fluid matrix (plasma)FunctionTransport respiratory gases, wastes, nutrients, immune response, and blood clottingLocationContained within blood vessels