2 Connective Tissue Most diverse tissue type Binds together, supports and strengthens other tissues.Protects and insulates internal organsCompartmentalizes structures – e.g. skeletal musclesMajor transport system – ?Store energy – ?Immune response – ?Two basic elements: cell and matrix – material between the cells.Matrix contains: protein fibers and ground substance – the material between the cells and the fibers.Nerve supply -- ?Usually highly vascular: Exceptions are cartilage and tendons.
3 Types of Cells Widely spaced – Not tight packed like epithelial cells. Fibroblasts that secrete the fibers and ground substance of the extracellular matrixMacrophages that are involved in the immune system (fixed and wandering)Mast cells produce histamine, a chemical that dilates small blood vessels as part of the inflammatory response – The body’s reaction to injury or infection.Adipocytes are fat cells
4 Extracellular Matrix Two main elements Ground substance – mostly water along with adhesion proteins and polysaccharide moleculesSupports cellsBinds cells togetherExchange of substances between blood and cellsFibersProduced by the cellsThree typesCollagen fibersElastic fibersReticular fibersThe matrix is firm in some parts of the body, but hard in others.Examples: ?
6 Fibers Collagen Fibers Made of protein called collagen Strong yet flexibleResist pulling forcesFound in:BoneCartilageTendonsLigaments
7 Fibers Elastic Fibers Thiner than collagen fibers Made of the protein, elastinCan be stretch without breakingFound in:SkinBlood vesselslungs
8 Fibers Reticular Fibers Much thinner than collagen fibers Provide support for stroma (covering) of soft organsFound in:Basement membraneNerve fibersMusclesSpleenLymph nodes
9 Connective Tissue Fibers Summary There are three types of connective tissue fiber, all made of protein:Collagenous fibers provide strength and flexibilityFound in: tendon, ligament, skin, cornea, cartilage, bone, blood vessels, gut, and intervertebral disc.Elastic fibers stretch and snap back to their original lengthFound in: Skin, blood vessel walls, lung tissueReticular fibers join connective tissue to adjacent tissuesFound in: liver, bone marrow, lymphatic organs, basement membrane
10 Quiz Which type of protein are collagen fibers made of? Which type of fiber provides support for soft organs?Which type of protein are elastic fibers made of?Which type of fibers can be found in blood vessels?Which type of fiber provides the greatest strength?
11 Ground SubstanceForms the material between the cells and fibers of connective tissue.Made of water, proteins, and polysaccharidesInstrumental in how tissues:DevelopMigrateProliferateChange shapeMetabolize
12 Connective Tissue Types six major types of connective tissue:Loose connective tissueDense connective tissueCartilageBoneBlood tissueLymph
14 Areolar Connective Tissue Forms the subcutaneous layer – Attaches skin to the underlying tissues and organsMade of collagen, elastic and reticular fibers.Made of fibroblast, macrophages, plasma, mast cells and adipocytes (fat cells)Figure 3.19e
15 Adipose Tissue Cells store fat. Functions Insulates the bodyProtects some organsServes as a site of fuel storageDoes an obese person have more blood vessels?Figure 3.19f
16 Reticular Connective Tissue Delicate network of interwoven fibersForms stroma of lymphoid organsLymph nodesSpleenBone marrowBind together smooth muscle cellsFilter worn out blood cells and bacteria.
17 Dense Connective Tissue More and thicker fibers but fewer cells than loose connective tissueMain matrix element is collagen fibersCells are fibroblastsExamplesTendon – attach muscle to boneLigaments – attach bone to boneFigure 3.19d
18 Dense Connective Tissue Dense RegularFibers arranged in parallel – RegularTendons and most ligamentsDense IrregularFibers not parallel – IrregularHeart valvesElasticCan extend and return to original lengthLungs, arteries
19 Connective Tissue Types Bone (osseous tissue)Composed of:Bone cells in cavitiesHard matrix of calcium saltsLarge numbers of collagen fibersUsed to protect and support the body
20 Connective Tissue Types Hyaline cartilageMost common cartilageComposed of:Abundant collagen fibersRubbery matrixEntire fetal skeleton is hyaline cartilageFigure 3.19b