<aside> 💡 Primary Tissue 2: Connective Tissue Structure and Function

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1. Explore the microscopic structure of the CTs and their diversity within the body.

   1. CT is found throughout the body

   2. the most abundant and widely distributed of primary tissues.

   3. They provide support for all organs and have a dynamic function in development, growth and homeostasis.

   4. These tissues all demonstrate cells in “mature” and “immature” forms allowing this tissue to grow and develop.

   5. Functions of CT include

      1. Binding and Support
      2. Protection
      3. Insulation
      4. Transportation

   6. Structural characteristics of CT include 2 basic elements

      1. cells not in contact with each other), scattered
      2. extracellular matrix (ECM)
         1. fibers
         2. ground substance

   7. Connective tissue: common embryological origin

      • Widely spaced cells separated by ECM
      • Hard ECM (bone) allow for tissue to provide support
      • Fluid ECM (blood) allows communication and transport throughout body

   8. Structure

      1. Cells (develops from mesenchyme)

         1. Resident (Maintain ECM, stores material)

            1. Fibroblasts (produce the ECM: fibres, ground substance)
            2. Adipocytes (lipid stores for energy/heat and physical protection/padding/insulation)
            3. Fixed Macrophages (phagocytic cells): phagocytosis of foreign material
            4. Mesenchyme cells (stem cells): spindle shaped, divides in response to injury

         2. Wandering Cells (Move through connective tissue spaces, Repair damaged ECM, Immune response )

            1. Mast Cells (release histamines, heparin to stimulate inflammation)
            2. Plasma Cell (forms antibodies that bind to antigens and pathogens)
            3. Free macrophages (phagocytic cells): phagocytosis of foreign material
            4. Leukocytes: Lymphocytes attack foreign material, neutrophils combat bacteria

            

            

            

            

      2. ECM

         1. Fibres
            1. Collagen
               1. Strong, stretch resistance
               2. Three helical subunits
               3. Fibrous, insoluble
               4. Most abundant protein in body
            2. Elastic/Elastin
               1. Flexible and resilient/stretchable, strong
               2. Made of elastin, fibrillin
               3. Skin, blood vessels, lung tissue
            3. Reticular
               1. Form loose interwoven network
               2. Collagen and glycoproteins
               3. Support in blood vessels, fat, smooth muscle, nerve
               4. Liver (hepatocyte shape), lymph nodes (structure, filtration)
         2. Ground Substance
            1. Amorphous gel like material
            2. Contains all components of the extracellular matrix (ECM) except for fibrous materials

   9. Types

      

      1. CT Proper

         1. Loose: more ground substance and cells, less fibres (loosely arranged)

            1. Areolar

               1. Fibroblasts, macrophages, adipocytes, mast cells, plasma cells
               2. Very little collagen, elastic, reticular fibres
               3. Loosely arranged fibres in gelatinous ground substance

               

            2. Adipose

               1. Adipocytes
               2. Reticular, collagen fibres
               3. Local fat deposit serve as nutrient reserve for highly active organs
               4. Densely packed cells, small amount of gelatinous ground substance

               

            3. Reticular

               1. Reticular cells lie in fibrous network
               2. Loose ground substance with reticular fibres
               3. Loosely arranged fibres in gelatinous ground substance
               4. Forms soft internal skeleton/structure/stroma that supports other cell types

               

         2. Dense: less ground substance and cells, more fibres

            1. Regular

               1. Parallel collagen fibers (regular), few elastic fibres
               2. Major cell type = fibroblast
               3. Less ground substance

               

            2. Irregular

               1. Fibroblast
               2. Collagen irregularly arranged

               

            3. Elastic

               1. irregularly arranged collagen Fibres with some elastic Fibres
               2. Major cell type: fibroblasts
               3. withstands tension in many directions providing structural strength
               4. Provides framework, supports organs
               5. Allows the tissue to return to its original length after stretching

               
      2. Fluid CT
      3. Supporting CT
2. Identify and recall the locations of the major different types of CT proper within the body.
3. Outline the characteristics of structural origin and function of the "connective tissue" class of tissues.
4. Outline the characteristics of structure and function of the supporting CTs of the body (cartilage and bone)
5. Relate the structures of the "CT proper" sub-classification to their functions within the body.
6. Relate the structures of the CT sub-classifications "bone" and "cartilage" to their functions within the body and their relationship to one another.