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: Regularly arranged in tendons,ligament 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.