Cell junctions

• What are the 3 types of cell junctions

  Impermeable. Adhesive. Communication.
• What are impermeable junctions


  Tight junctions
• What are the adhesive junctions


  Adheren and Desmoses.
• What are the types of communication junctions


  Gap junctions and chemical synapses.
• Impermeable junctions

  Prevent the passage of molecules between adjacent cells
• Adhesive junctions

  Mechanically hold cells together
• Communication junctions

  Allow passage of small molecules between cells
• Tight junctions

  Separate the apical and basal plasma membranes
• Adherens junctions

  Connect the cell to actin filaments
• Desmosomes

  Connect the cell to intermediate filaments
• Function of adherens junctions

  Regulates intracellular signalling
• Function of desmosomes

  Provide structural integrity by withstanding mechanical stress
• Types of desmosomes

  • Belt
  • Spot
  • Hemi-desmosomes
• Hemi-desmosomes

  Attach the base of the cell to the basal lamina
• Structure of a gap junction

  Pores made of connexin, each cell provides 6 connexins, and so there are 12 in total
• Permeability of gap junctions

  Affected by changes in intracellular pH or Calcium levels
• What is a tissue

  It is made of specialised cells with different functions
• What is the function of epithelial tissue

  • Protect against mechanical injury
  • Provide a barrier against microbes and fluid loss
• Describe the structure of epithelial cells

  Made of sheets of tightly packed cells.

  It can be simple [1 layer] or stratified [Multiple layers].
• Where is epithelial tissue found

  On the outside of the body and as the lining of organs.
• What junctions are often found in epithelial tissue

  Desmosomes and tight junctions.
• What type of tissue is this

  Simple Squamous epithelium

  
• What type of tissue is this

  Stratified squamous epithelium

  A)

  
• What type of tissue is this

  Pseudostratified columnar epithelium

  
• What type of tissue is this

  Simple columnar epithelium

  
• What type of tissue is this

  Cuboidal epithelium

  
• What are thee types of epithelium tissue

  • cuboidal
  • Simple columnar
  • Pseudostratified columnar
  • Simple squamous
  • Stratified squamous
• What is the main function of connective tissue

  To provide mechanical strength. Bind and support tissues.
• What are the main types of connective tissue.

  Dense.

  Loose.

  Blood.

  Adipose.
• What are examples of dense connective tissue

  Bone Cartillage and tendons
• What are the features of dense connective tissue

  Provides great mechanical strength and elasticity.

  Consits of the Extracellular matrix with few cells.
• What is dense connective tissue made of

  Fibrous proteins

  Ground substances
• What fibrous proteins are found in dense connective tissue

  Collagen and Elastin.
• What ground substances are found in dense connective tissue

  Proteoglycans
• What is the function of loose connective tissue

  To hold small glands and epithelium together. It also includes the basal lamina of cells.
• Desccribe the formation of collagen fibrils

  Lateral interactions form between the triple helices.
• What is the role of muscle tissue


  To support movement.
• Describe the structure of muscle tissues

  They are made of long excitable cells containing actin and myosin filaments.
• What is a myofibril

  A division wihin a muscle fibre. It consists of thin or thick filaments.
• What are thin muscle filaments made fo

  Actin