Connective tissue

• Stem cells


  Inner cell mass becomes the baby
• 4 Types of Tissue

  • Epithelial
  • Connective
  • Muscle
  • Neural

  
• Connective Tissue


  • Wide variety of structural features
  • Wide variety of functions
  • Connects other structures and tissues
  • Binds together
  • Nutritional support
  • Site of defense reactions
  • Transmits and resists forces
  • Skeletal support

  
• Classification of Adult Connective Tissues

  • Fibres 3 type (also called "formed" elements)
  • Ground substance ("Amorphous")
  • Cells

  
• Extracellular matrix (ECM)


  Large amount of intercellular substance
• Fibres of extracellular matrix (ECM)


  • Collagen
  • Elastic
  • Reticular

  
• Ground Substance


  Fills space between cells & surrounds fibers, made of Hyaluronic acid, proteoglycans and glycoproteins
• Glycosaminoglycans


  Component of ground substance
• Proteoglycans


  Component of ground substance
• Glycoproteins


  Component of ground substance
• CT Proper: Cell types

  • Fixed cells: Fibroblasts, Macrophages, Adipocytes, Melanocytes
  • Wandering cells: Macrophages, Mast cells, Lymphocytes

  
• Fibroblasts

  Undifferentiated cells, make CT, most abundant & ALWAYS present

  
• Macrophages


  Attack pathogens & damaged cells, initiate immune response
• Adipocytes


  Energy storage
• Melanocytes


  Determine skin & eye color
• Mast cells


  Secrete histamine and heparin
• Lymphocytes


  T cells and B cells - immunity
• White blood cells


  Normal components of some connective tissues, leave blood vessels to perform functions in surrounding connective tissue
• Adipocytes


  Very large cells containing major lipid inclusions, nucleus and cytoplasm pushed to periphery

  
• Brown fat cells

  Smaller, contain several fat droplets, more mitochondria
• Adipocytes and capillaries


  Close relationship, facilitates exchange between fat and blood
• Storage and release of lipid by adipocytes

  Lipids transported through blood as chylomicrons and VLDL, hydrolyzed by lipoprotein lipase, fatty acids diffuse into fat cell and reesterified, triglycerides mobilized by hydrolysis as needed
• Connective Tissue


  • Embryonic: mesenchymal, mucous
  • Adult

  
• Mesenchymal Connective Tissue


  • Cells are spindle or stellate shaped, large euchromatic nuclei, minimal cytoplasm, ground substance rich in hyaluronan and water, homogeneous and fluid, no extracellular fibers

  
• Mucous Connective Tissue


  • Cells similar to mesenchymal, ground substance very viscous and "slimy" due to high hyaluronan, collagenous fibrils and fibers minimal but increase with time

  
• Classification of Adult Connective Tissues

  • Loose: Areolar, Adipose, Reticular
  • Dense: Regular, Irregular
  • Elastic

  
• Loose Connective Tissue


  • Fewer fibres, abundant ground substance, supports epithelia, mechanical support, site of tissue fluid formation, site of initial defense reactions

  
• Loose Connective Tissue


  • Areolar, Adipose, Reticular

  
• Areolar Connective Tissue


  Fine, whitish, cobweb-like and stretchy, found around muscles, blood vessels, nerves, organs, fills spaces and provides internal framework

  
• Adipose Tissue


  Nutritive, protective, insulative, cosmetic, widely distributed
• Reticular Connective Tissue


  Fine, net-like support for lymphoid and myeloid organs

  
• Types of Dense Connective Tissue

  • Dense Regular: tendons, aponeuroses, ligaments
  • Dense Irregular: encapsulates organs, surrounds bone and cartilage

  
• Dense Regular Connective Tissue

  Fibers parallel, tightly packed, aligned with applied forces

  
• Dense Irregular Connective Tissue

  Fibers interwoven, no pattern, applied forces from many directions

  
• Dense Regular Connective Tissue

  • Tendons, Aponeuroses, Ligaments

  
• Elastic Connective Tissue


  Permits some expansion without damage and regains shape
• Elastic connective tissue is found in some ligaments and is yellowish in color</b>

  
• Mucosa, muscle, lining epithelium, supporting connective tissue, and neurons/nerve plexuses are integrated as seen in the intestine