Connective tissues

• Connective Tissues

  • Connective tissue lies under the epithelia of all tissues and organs.

  • Connective tissue is a diverse primary tissue type that makes up part of every organ in the body.

  • Connective tissue differs from the other three tissue types in that it consists of cells separated from each other by abundant extracellular matrix.

  • Connective tissue is diverse in both structure and function.

  • Connective tissue is comprised of cells, protein fibers, and an extracellular matrix
• Functions of Connective Tissues

  1. Enclose and separate other tissues

  2. Connecting tissues to one another

  3. Supporting and moving parts of the body

  4. Storing compounds

  5. Cushioning and insulating

  6. Transporting

  7. Protecting
• Connective Tissue Cells

  • The specialized cells of the various connective tissues produce the extracellular matrix

  . • The name of the cell identifies the cell functions.

  • Osteoblasts form bone, osteocytes maintain it, and osteoclasts break it down.

  • Fibroblasts are cells that form fibrous connective tissue, and fibrocytes maintain it.

  • Chondroblasts form cartilage and chondrocytes maintain it
• Cells associated with the immune system, such as white blood cells, are also found in connective tissue.

  • Macrophages are large cells that are capable of moving about and ingesting foreign substances, including microorganisms in the connective tissue.

  • Mast cells are nonmotile cells that release chemicals, such as histamine, that promote inflammation.
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  • The Extracellular Matrix of connective tissue has three major components: protein fibers, ground substance, and fluid.

  • Ground substance consists of non-fibrous protein and other molecules.

  • The structure of the matrix is responsible for the functional characteristics of connective tissues—for example, they enable bones and cartilage to bear weight
• Matrix Protein Fibers

  • Three types of protein fibers—collagen, reticular, and elastic—help form most connective tissues.

  • Collagen fibers, which resemble microscopic ropes, are very flexible but resist stretching.

  • Reticular fibers are very fine, short collagen fibers that branch to form a supporting network.

  • Elastic fibers have the ability to return to their original shape after being stretched or compressed, giving tissue an elastic quality
• • The matrix ground substance consists of non-fibrous molecules and is shapeless.

  • It consists of proteoglycans, which are large molecules that consist of a protein core attached to many long polysaccharides.

  • Proteoglycans trap large quantities of water between the polysaccharides, which allows them to return to their original shape when compressed or deformed
• Types of Connective Tissues

  • The organization of the extracellular matrix varies from:

  • loose irregular (where the numbers of cells and fibrous proteins are relatively low); to

  • dense irregular (where there are more cells, and fibers); to

  • dense regular (where the fibers are densely packed, and regularly arranged).

  • specialized connective tissues
• Loose connective tissue, areolar

  Description: Gel-like matrix with all three fiber types (collagen, elastic and fibroblast fibers); cells: fibroblasts, (a) Connective tissue proper: loose connective tissue, areolar macrophages, mast cells, and some white blood cells.

  
• loose connective tissue, adipose

  
• loose connective tissue, reticular

  
• Dense regular connective tissue

  
• dense irregular connective tissue

  
• Dense regular elastic connective tissue

  
• Hyaline cartilage

  
• Elastic Cartilage