Cell Modification

• Cell Modification


  Refers to the structural and functional changes that cells undergo to adapt to specific tasks or environmental conditions.
• Apical Modification


  –      Cell modification found on the apical surface of the cell.
• Cilia

  -      Hair-like structures that extend from the apical surface of certain cells, such as those lining the respiratory tract or fallopian tubes.
• Cilia


  Function: Cilia move rhythmically to     propel mucus, dust, or other particles along the surface. In the fallopian tubes, cilia help move the egg towards the uterus.
• Flagella


  -      is a long, whip-like structure that protrudes from the surface of certain cells, providing motility. 
• Vili


  -      are larger, finger-like projections of the intestinal wall that increase the surface area available for nutrient absorption.
• Vili


  Function: Increase surface area for absorption, particularly in the intestines and kidneys. These structures are important for nutrient absorption and other substances.
• Microvili


  -      are microscopic, hair-like extensions of the plasma membrane found on the surface of the epithelial cells that make up the villi.
• Microvili


  Function: Microvilli further increase the surface area for absorption and contain enzymes that aid in the final steps of digestion.
• Pseudopods


  aka PSEUDOPODIA "false feet"
• ECM


  –      is a complex network of proteins and other molecules that exist outside the cells in tissues.

   

       Function:

       Structural support

       Cell Adhesion and Movement

       Cell Signaling

       Tissue Development and Repair

       Regulation of Cellular Behavior.
• Basal Modification


  o   refers to structural changes that occur at the basal surface of epithelial cells, which is the surface attached to the underlying tissue, usually connected to the basement membrane. 
• Hemidesmosomes


  -      are specialized structures that anchor epithelial cells to the underlying basement membrane. They connect the cell's cytoskeleton to the extracellular matrix.

   

  Function: These structures provide strong attachment and resist shearing forces, especially in tissues that undergo a lot of mechanical stress, such as the skin.
• Lateral Modification


    refer to specialized structures found on the lateral surfaces of epithelial cells, where adjacent cells are connected.

   

  Functions: 

  Cell Adhesion

  Barrier Function

  Communication 
• Tight conjunctions (zonula occludens)


  -      are structures that form a seal between adjacent cells, preventing substances from passing between the cells in epithelial layers. 

   

  Function: They create a barrier that regulates the movement of water, ions, and other solutes across the epithelium. This is crucial in tissues like the intestines and blood-brain barrier, where selective permeability is essential.
• Adherens junctions (zonula adherens)


  -      are adhesive junctions that connect the actin cytoskeleton of one cell to that of its neighbor via cadherin proteins.

   

  Function: These junctions help maintain the structural integrity of tissues, providing strong mechanical attachment between cells to resist mechanical stress, such as stretching.
• Gap junction


  -      are specialized channels that allow direct communication between adjacent cells by permitting ions, nutrients, and small molecules to pass through.

  Function: These junctions enable rapid communication between cells, facilitating coordinated activity, especially in tissues that require synchronization, such as cardiac and smooth muscle.