Connective Tissue

Connective Tissue Characteristics of connective tissues •Extracellular matrix separates cells •Most widely variable of tissues •Many varied functions •Common (mesenchyme) origin •Degrees of vascularity Functions •Binding •Suport •Protection •Insulation •Transport Structural Elements •Fibers ?Collagen (white) fibres ?Elastin (yellow) fibers ?Reticular fibers •Ground substance ?Amorphous material fills space between cells and contains fibers ?Holds fluids ?Acts as molecular sieve ?Consists of interstitial fluid, cell adhesion proteins “glue”, proteoglycans •Cells Each class of connective tissue has a fundamental cell type that exists in an immature and mature form ?Undifferentiated cell gets suffix “blast” i. e chronoblast, they are actively mitotic, secrete fibers and ground subtance ?Once the cells synthesise the matrix they assume their less active mature mode indicated by suffix “cyte” i. e. lymphocyte Summary Fibers Ground Substance Cells Collagen Interstitial fluid Immature form “blast” Elastin Cell adhesion proteins “glue” Mature form “cyte” Reticular Proteoglycans Types of connective tissue •All consist of cells surrounded by matrix Differences reflect cell type, finer type and the proportion of matrix contributed by fivers •These differences determine connective tissue classes and their subgroups ?General (fibrous) connective tissue “proper” ?Specialised Connective tissues (skeletal – bone and cartilage, adipose, lymphoid, blood) Cells found in ‘Prototype’ Connective Tissue •FIbroblasts •Adipocytes (fat cells) •Cells which migrate from blood ?WBC ?Other cells concerned with tissue response to injury Connective Tissue Proper Two subgroups – classification mainly based on finer arrangement and density: •Loose CT Areolar ?Reticular •Dense CT ?Dense regular ?Dense irregular Connective Tissue Proper Sub groups Characteristics/Structural elements Loose Areolar Semi fluid Gelatinous ground substance Collagen, elastin, reticular loosely distributed Fibroblasts and macrophages are abundant Occasional adipocytes (fat cells) Widely distributed packing material of body Loose Reticular Matrix contains reticular fibers Reticular fibers form network of reticular cells (fibroblasts) Dense Regular Closely packed collagen fibers orientated in same direction Mainly fibroblasts Poorly vascularised (no blood vessels)

White, flexible tissue with great tensile strength in one direction Wavy fivers – allow minimal ‘give’ until fibbers are straightened Elastic CT has high elastic content i. e. ligaments and tendons Dense Irregular Closely packed collagen fibers orientated in same direction Mainly fibroblasts Poorly vascularised (no blood vessels) Collagen bundles are orientated in MANY directions Forms sheets where tension is exerted in from many directions i. e. dermis of skin, fibrous joint capsules, fibrous capsules of many organs (kidneys, testis, bone, muscles) Blood •Classified as a connective tissue •Cells in matrix (plasma) Fibers are soluble proteins which only become visible during clotting •Functions ?Transport of nutrients (glucose, oxygen) ?Transport of wastes (CO2) ?Transport of gases (oxygen, CO2) ?Hormones Cartilage •Somewhere between dense CT and bone •Tough but flexible •Cartilage cells “chondro” prefix •Ground substance has firmly bound collagen fivers •Contains lots of tissue fluid (80% water) •No blood vessels or nerves (good for joints) •Perichondrium (dense irreg. CT) surrounds most cartilage •Growth both interstitial and appositional •Types: ?Hyaline ?Elastic ?Fibrocartilage Bone “Bone” can refer to: Osseous tissue (type of CT) •Organs of the body i. e. humerus (consisting of several tissue types) Bone as a tissue •Bone is connective tissue (osseous tissue) •Cells contained in a matrix •Matrix is hardened by deposition of calcium salts and other minerals = calcification (mineralisation) Functions of bony skeleton •Support •Protection •Rigid attachment •Levers for muscles •Blood formation •Electrolyte balance •Acid base balance •Detoxification General features of long bone •Compact bone •Spongy bone •Medullary cavity •Diaphysis (shaft) •Epiphysis •Epiphysis plate/line •Articular cartilage •Periosteum and endosteum