Connective Tissue PDF

The connective tissue General characters : 1- Derived from mesoderm. 2- No basement membrane. 3- Consists of a variety of widely spaced cells within an intercellular matrix...

The connective tissue General characters : 1- Derived from mesoderm. 2- No basement membrane. 3- Consists of a variety of widely spaced cells within an intercellular matrix. 4- Matrix may be loose or dense. 1  Functions of connective tissues: 1- Performs diverse functions as binding, support, protection, and transport. 2- Many types of fibrous C.T hold organs together. 3- Help in transport of nutrients,signaling factors because it contain many blood vessels. 4- Defence against pathogenic organisms ( macrophage). 5- Heal of wounds (‫ (الجروح‬and repair of damage to itself. 6- Help in conserving the body tempreature, thermogenesis, and insulation ‫العزل‬. 2  Classification of connective tissues according to the nature of intercellular substance or matrix, the connective tissue is classified into. Connective tissue Proper Vascular C.T. Gelatinous or soft intercellular With fluid intercellular substance substance ( blood , lymph) Skeletal C.T. With solid or semisolid intercellular Substance ( cartilage , bone ) 3 Connective tissue proper Contain the following types; 1- Areolar or loose C.T. 2- White or fibrous C.T. 3- Yellow or elastic C.T. 4- Reticular C.T. 5- Mucous C.T. 6- Adipose C.T. 4 5 6 7 Areolar (loose C.T.) 8  Found in the skin and in most internal organs of vertebrates where it allows the organ to expand. Ground substance is a viscous (jelly like) clear substance. Loose C.T. contains 3 kinds of fibers 1- White ( collagenous fibers), - Made of a protein collagen ( glycoprotein), (fibroblast). - high tensile ‫ الشد‬strength with some flexibility. - exhibite a white colour in dense collection of bundles. - each fibre is actually an aggregation of many parallel fine fibrils , fibers and fibrils not branched but bundles generally divided into smaller bundles. - ex: tendons where muscles connected to bones, ligaments , pericardium. 9 10  2- Yellow ( elastic fibres): - elastic fibers made of protein ( elastin). - thin single branching fibres. - elastic and capable of stretched, branched and form network. - present where flexability and elastic recoil are needed. - arteries, trachea and bronchi. 3- Reticular fibres: -formed from collagen but thinner. - thin , branching and forming extensive network. - form a fine branching network fibers within organs. - also found in between the smooth muscle fibers. - have a supportive function. 11  Cells of Loose connective tissue - Fibroblasts,……. Called mother cells and have the ability to form many fibers. - develop from undifferentiated mesenchymal cells. - large, flattened , with several fine branches, with dark stained nuclei,acidohpilic ctoplasm. - Functions; formation of collagen , elastic fibers, ground substances, help in wound healing. 12  Macrophages (histiocytes): - Large cells with eccentric round or bean- shape nuclei, abundant basohpilic cytoplasm , rich in lysosoms. - Function; defence by engulfing foreign bodies. Mast cells: largest and abundant in the aeolar C.T. cytoplasm filled with basophilic granules contain histamine , heparin. - Round and centrally located nucleus. - Release of granules content and to effects of these substances on the organism. 13 14  Pigment cells : elongated, branched, their cytoplasm rich in pigment granules (melanin). Called chromatophores. Adipose cells: large cells , spherical or polyhedral in shape. - Cytoplasm is occupied with by a single large lipid droplet , which pushes the cytoplasm and the nucleus to thin peripheral ring. - Function: storage fat. 15  Plasma cells: large spherical or ovoid cells, non granular basophilic cytoplasm , eccentrically spherical nuclei with dark stained chromatin masses, clock face or cart wheel. Function: synthesis of antibodies. Leukocytes: white blood cells that migrate across the wall of blood capillaries during inflammation to do their function. eosinophil and lymphocytes. Acidophil, Increase in chronic increase in inflammation acute inflammation 16  2-white or fibrous C.T. 3- Yellow or elastic C.T. - Mainly formed of - mainly formed of collagen. elastin. - Very thin elastic fibers - Thin branching, give (network) formed elasticity. between collagenous fibers. - Run in all directions. - ex; tendons, ligaments. - Give elasticity and flexibility. - Ex; arteries, trachea. 17  4- Reticular C.T: - very fine type of c.t. - they are long processes form a network which support tissues, cells,organs. - ex; bone marrow, liver sinusoids and pancreatic islets. 5-Mucous C.T: - Composed of jelly like intercellular substance rich in polysaccharides. - ex; umbilical cord, embryonic c.t. 6- Adipose C.T: - Characterized by fat cells. - ex; subcutaneous layer 18