Lesson 4-Specialized Connective Tissue Proper

• 4 Main Groups of Connective Tissues

  • Connective Tissue Proper
  • Bone
  • Cartilage
  • Blood
• Connective Tissue Proper

  Most diverse group of tissues, supports and binds tissues for all organs
• Origin of Connective Tissues

  Mesenchyme - loose and fluid type of embryonic tissues, common origin of all connective tissues
• Mesenchymal Cells


  • Can be situated in any way and can move from place to place, unlike epithelial cells which have fixed and neatly arranged in sheets
• Characteristics of Connective Tissues


  • Different degrees of vascularity (blood flow)
  • Cartilage - avascular
  • Dense irregular tissue in skin - vascular
  • Cells are separated by a large amount of Intercellular space
• Components of Connective Tissues


  • Extracellular Matrix
  • Ground Substance
  • Fibers
• Ground Substance


  Watery, rubbery, unstructured material that fills the spaces between cells, protects the cells in the extracellular matrix, flexible - made of starch, protein molecules and water
• Ground Substance Components


  • Proteoglycans - anchors this framework
  • GAG or Glycosaminoglycans - sprouts from proteoglycans
• Fibers


  Provide support and structure to the otherwise shapeless ground substance
• Types of Fibers


  • Collagen - strongest and most abundant, tough and flexible
  • Elastic Fibers - longer and thinner, form a branching framework, made of protein elastin, allows them to stretch and recoil
  • Reticular Fibers - short, finger collagen fibers with an extra coating of glycoprotein, forms a delicate, sponge-like networks that cradle and support the organs
• Blasts


  Stem cells or immature cells, undergo mitosis to replicate themselves, has different types with different functions, once they mature they transition from -blast to -cyte
• Blast Cell Types


  • Chondroblast - blast cells of cartilage
  • Osteoblast - blast cells of the bone tissue
  • Macrophages - provide immune defense for connective tissues, phagocytize bacteria, foreign materials and dead cells
• Collagen Fibers


  • Strongest and most abundant type of fiber, appear neat and smooth "white, flexible" structures under the microscope, provides great resistance to tension
• Elastic Fibers


  • Form a branching framework, stretch and recoil like rubber bands
• Reticular Fibers


  • Short, finer collagen fibers, sponge like networks
• Types of Connective Tissue Proper


  • Loose Connective Tissue - Areolar, Adipose, Reticular
  • Dense Connective Tissue - Regular, Irregular, Elastic
• Loose Connective Tissue


  Have fewer fibers, and more cells and more ground substance
• Types of Loose Connective Tissue


  • Mesenchyme - embryo, fetus
  • Mucoid - Wharton's jelly or umbilical cord
  • Adipose - subcutaneous tissue (dermis)
  • Reticular - bone marrow, lymph node, spleen
• Dense Connective Tissue


  • Regular - tendon, stroma of cornea
  • Irregular - dermis, capsules of organs
• Tendon


  Dense connective tissue that connects your bone to muscle and muscle to muscle
• Ligament


  Dense connective tissue that connects your bone to bone
• Areolar Connective Tissue


  Most common loose connective tissue, found all over the body under the epithelial tissues and wrapped around the organs, has loose and random arrangement of fibers, few fibroblast cells, has a lot of open space, effective in holding the watery, salty ground substance
• Adipose Connective Tissue


  Fat tissue, the average person's weight is about 18% adipose tissue or fat stores, provides insulation against heat loss, provides fuel storage and keeps us alive during starvation or fasting, is mostly cells - adipocytes - which store lipids for later use
• Reticular Connective Tissue


  Holds your blood cells in place in many of the blood forming organs, similar to areolar tissue but with a woven mass of reticular fibers instead of collagen and elastin fibers, provides the soft internal framework or stroma of the spleen, lymph nodes and bone marrow, supports developing blood cells and holds your blood in place inside the organs
• Regular Dense Connective Tissue

  Collagen fibers are stacked neatly in regular rows
• Irregular Dense Connective Tissue


  Collagen fibers are not stacked regularly in rows, fibers are thicker and arranged erratically, found wherever tension might be exerted in lots of different directions such as the leathery dermis under the skin
• Elastic Connective Tissue


  Collagen with interwoven elastic fibers, found in places in the body that requires more elasticity and rigidity such as around the joints, connecting the vertebrae so the spine can curve and twist, component of arteries - to provide support and flexibility