Basic Tissues

• what is epithelia?

  layers of cells that line the surfaces of the body and its organs, both externally and internally
• locations of epithelia?


  cover surfaces

  live cavities and tubes

  forms glands
• important characteristics of epithelia?


  attachment

  avascularity

  regeneration

  polarity (apical and basal)
• label them?

  A and B

  A) A

  B) B

  
• types of epithelia?


  simple squamous

  keratinised stratified squamous

  non keratinised stratified squamous

  simple cuboidal

  simple columnar

  pseudostratified columnar with goblet cells
• simple squamous?


  flat cells - oval shaped nuclei

  one layer of cells

  function - exchange of nutrient & gases

  location - blood vessels, alveoli.

  
• keratinised stratified squamous

  • flat surface cells with oval shaped nuclei
  • many layers
  • keratin
  • function - protection, barrier (waterproof)
  • location - skin

  
• non-keratinised stratified squamous


  flat surface cells with oval shaped nuclei

  many layers

  function - protection, barrier

  location - oral cavity, oesophagus

  
• simple cuboidal epithelium


  square cells with round nuclei

  one layer

  function - secretion and absorption

  location - glands, kidney tubules

  
• simple columnar epithelium


  tall cells with oval, basally located nuclei

  one layer

  function - absorption and secretion

  location - gastrointestinal tract

  surface modifications - microvilli

  
• pseudostratified ciliated columnar epithelium with goblet cells

  • tall cells
  • appears stratified as some cells don't reach free surface
  • all cells touch basement membrane
  • function - mucociliary escalator
  • location - trachea & large respiratory airways

  
• which epithelia it is:

  ?

  A) ?

  
• what are intercellular junctions?


  specialised areas of cell membrane that bind one cell to another
• examples of intercellular junctions

  desmosomes

  hemidesmosomes

  tight junctions

  gap junctions

  A) 1

  B) 2

  C) 3

  D) 4

  
• desmosomes

  • very strong connections between adjacent cells
  • function - resist stretching and twisiting
• hemidesmosomes


  attach cells to the basement membrane

  function - stabilise the position and anchor cell to the underlying tissue
• tight junctions


  interlocking proteins tightly bind cells together near apical edge

  function - prevent passage of water and solutes between cells (e.g. in digestive tract)
• gap junctions


  cells held together by an interlocking membrane proteins containing a central pore

  function - allows movement of small molecules and ions between cells - found in cardiac muscle
• what does connective do

  • structural frame for the body
  • supports, surrounds & interconnects other tissue types
  • protect delicate organs
  • transport fluids and dissolved materials
  • stores energy reserves
  • defends body fro microorganisms
• what is connective tissue consisted of?


  consists of cells within an extracellular matrix
• which cells are connective tissue


  fibroblasts: the main cell type, synthesizes the extracellular matrix

  adipocytes (fat cells)

  macrophage and mast cells (lymphocytes)
• what is extracellular matrix consists of?


  ground substance

  tissue (extracellular) fluid

  fibres; collagen, reticular & elastic
• classification of connective tissue

  • specialised connective tissue
  • connective tissue proper
• what are specialised connective tissues

  blood, bone, cartilage

  A) a

  
• what is connective tissue proper

  fill the gaps in between organs -> packages the body

  A) a

  B) b

  C) c

  
• loose (areolar) connective tissue


  contains:

  • lots of ground substance
  • few fibres (collagen & elastic)
  • cells; fibroblasts, adipocytes, macrophages

  found under the epithelium that covers & lines the body surfaces

  
• dense irregular connective tissue


  contains:

  • little ground substance
  • many collagen fibre bundles - arranged haphazardly
  • few cells (mainly fibroblasts)

  resists excessive stretching & distension

  found in dermis

  
• dense regular connective tissue


  contains:

  • little ground substance
  • many densely packed bundles of collagen fibres in parallel rows
  • few cells (mainly fibroblasts)

  found in tendons and ligaments

  
• muscle tissue and types of them

  • produces movement and is specialised for contraction
  • skeletal, smooth & cardiac
• similarities in muscle tissues

  • elongates parallel to axis of contraction
  • numerous mitochondria
  • contractile elements
• function of skeletal muscle?

  • moves and stabilises the skeleton
  • forms sphincters (ring of muscle controlling opening/closing) in digestive and urinary tracts
  • involved in respiration

  
• characteristics of skeletal muscle

  • long, cylindrical cells
  • striated (striped)
  • multi-nucleated
  • innervated by somatic nervous system

  
• function of smooth muscle

  • found in the walls of organs, blood vessels & airways
  • gastrointestinal movement
  • alters diameter of airways & blood vessels

  
• characteristics of smooth muscle

  • short, fusiform cells
  • non-striated
  • single, nucleus in the centre
  • innervated by autonomic nervous system

  
• function of cardiac muscle

  • found in the heart wall
  • helps to circulate blood & to maintain blood pressure
• characteristics of cardiac muscle


  branched muscle fibresbranched muscle fibresbranched muscle fibresbranched muscle fibres

  striated

  1-2 central nuclei

  intercalated discs

  innervated by autonomic NS