Connective Tissues Lecture PDF

Connective Tissues - Introduction 4 Types of Tissues  Epithelial Covers body surfaces and lines hollow organs, body cavities, ducts, and forms glands  Connective Protects, supports, and binds organs. Stores energy as fat, provides immunity  Muscular Gen...

Connective Tissues - Introduction 4 Types of Tissues  Epithelial Covers body surfaces and lines hollow organs, body cavities, ducts, and forms glands  Connective Protects, supports, and binds organs. Stores energy as fat, provides immunity  Muscular Generates the physical force needed to make body structures move and generate body heat  Nervous Detect changes in body and responds by generating nerve impulses Development of Tissues Tissues of the body develop from three primary germ layers: Ectoderm, Endoderm, and Mesoderm  Epithelial tissues develop from all three germ layers  All connective tissue and most muscle tissues derive from mesoderm  Nervous tissue develops from ectoderm Connective Tissue Most abundant and widely distributed tissue in the body Numerous functions  Binds tissues together  Supports and strengthen tissue  Protects and insulates internal organs  Compartmentalize and transport  Energy reserves and immune responses Extracellular matrix of Connective Tissue Extracellular matrix is the material located between the cells  Consist of protein fibers and ground substance Connective tissue is highly vascular Supplied with nerves  Exception is cartilage and tendon. Both have little or no blood supply and no nerves Connective Tissue Cells Fibroblasts  Secrete fibers and components of ground substance Adipocytes (fat cells)  Store triglycerides (fat) Mast cells  Produce histamine White blood cells  Immune response  Neutrophils and Eosinophils Macrophages  Engulf bacteria and cellular debris by phagocytosis Plasma cells  Secrete antibodies Connective Tissue Extracellular Matrix Ground substance  Between cells and fibers Fluid, semifluid, gelatinous, or calcified  Functions to support and bind cells, store water, and allow exchange between blood and cells  Complex combination of proteins and polysaccharides Fibers  Collagen fibers  Elastic fibers  Reticular fibers Classification of Connective Tissues Mature connective tissue (proper)  Loose connective tissue Areolar, adipose, and reticular  Dense connective tissue Dense regular, dense irregular, and elastic  Cartilage Hyaline, fibrocartilage, and elastic cartilage  Bone tissue  Liquid connective tissue Blood and lymph Embryonic Connective Tissue  Mesenchyme Gives rise to all other connective tissues  Mucous (Wharton’s Jelly) Found in umbilical cord of the fetus Embryonic Connective Tissue Mesenchyme  Found in the embryo  Small, spindle shaped cells, uniform appearance  Cells extend processes to form networks  A viscous ground substance between cells with little collagen Loose Connective Tissue A cellular CT with thin and relatively sparse collagen fibers Abundant ground substance with viscous consistency Facilitates diffusion of O2 and nutrients from circulation Located primarily beneath epithelia at body surfaces Surrounds glands and blood vessels Loose Connective Tissue The initial site of pathogen encounter if epithelia are breached Contains resident and wandering immune cell populations Site of inflammation Loose Connective Tissue: Areolar Connective Tissue  Most widely distributed in the body  Contains several types of cells and all three fibers Loose Connective Tissue: Adipose  Tissue Contains adipocytes  Insulation and energy reserves  Hormone production and proinflammatory cytokines  White (common) and brown adipose tissue Loose Connective Tissue: Reticular Connective Tissue  Fine interlacing reticular fibers and cells  Forms the stroma of liver, spleen, and lymph nodes Dense Connective Tissue Dense connective tissue  Contains numerous, thicker, and denser fibers  Packed closely with fewer cells than loose connective tissue Dense regular connective tissue  Bundles of collagen fibers are regularly arranged in parallel patterns for strength  Tendons and most ligaments Types of Mature Connective Tissue: Dense Irregular Connective Collagen fibers are Tissue usually irregularly arranged  Found where pulling forces are exerted in many directions  Dermis of skin and heart Dense Connective Tissue: Elastic Connective Tissue  Contain branching elastic fibers  Strong and can recoil to original shape after stretching  Lung tissue and arteries Types of Mature Connective Tissue: Cartilage Cartilage is a dense network of collagen fibers and elastic fibers firmly embedded in chondroitin sulfate  Chondrocytes Cartilage cells found in the spaces called lacunae  Perichondrium Covering of dense irregular connective tissue that surrounds the cartilage Two layers: outer fibrous layer and inner cellular layer  No blood vessels or nerves, except perichondrium Cartilage Composed of chondrocytes (cells) located in matrix- surrounded spaces called lacunae. Type of cartilage determined by components of the matrix. Firm consistency. Ground substance: Proteoglycans and hyaluronic acid complexed together trap large amounts of water Allows tissue to spring back after being compressed.. Perichondrium. Dense irregular connective tissue that surrounds cartilage. Fibroblasts of perichondrium can differentiate into chondroblasts (cartilage-forming cells) Types of cartilage  Hyaline  Fibrocartilage  Elastic Hyaline cartilage  Most abundant cartilage in the body  Surrounded by perichondrium (some exceptions like articular cartilage)  Provide flexibility and support. Reduces friction Copyright 2009, John Wiley & Son s, Inc. Fibrocartilage  Chondrocytes are scattered among bundles of collagen fibers within the extracellular matrix  Lack a perichondrium  Strongest type of cartilage  Found in intervertebral disc (between vertebrae) Elastic Cartilage  Chrondrocytes are located within a threadlike network of elastic fibers  Perichondrium is present  Provides strength and elasticity Repair and Growth of Cartilage Cartilage grows slowly When injured or inflamed, repairs is slow due to its avascular nature. Two patterns of cartilage growth:  Interstitial growth Growth from within the tissue  Appositional growth Growth at the outer surface of the tissue Bone tissue Bones are organs composed of several different connective tissues: bone (osseous) tissue, periosteum, and endosteum. Compact or spongy Osteon or Haversian system  Spongy bone lacks osteons. They have columns called trabeculae Fluid Connective Tissue Blood tissue  Connective tissue with liquid extracellular matrix called blood plasma Lymph