basic tissues

• Organisation of the body

  1. Cell: functional unit of the body
  2. Tissue: collection of cells performing a particular function
  3. Organ: multiple tissues working together performing a particular function
  4. System: group of organs with a collective function
  5. Organism: complete individual
• Four types in which the whole body is made of:

  • Epithelia
  • Connective tissue
  • Muscle
  • Nervous
• Epithelia

  • Covers body surface, lines cavities and tubes, forms glands
  • Characteristics: avascularity, attachment, regenerative and polarity
  • Consists of loosely packed cells supported by a basement membrane
• Classification of epithelia

  Number of cell layers

  • Simple = one layer
  • Striated = two or more layers
  • Shape (nucleus reflects shape)
  • Squamous = flat
  • Cuboidal = square
  • Columnar = rectable
• 1. Simple squamous

  • Oval nuclei
  • Exchange nutrients and gases
  • Found in blood vessels and alveoli
• Keratinised stratified squamous

  • Oval nuclei
  • Produce keratin
  • Used for protection (keratin acts as a waterproof barrier)
  • Found in skin and mouth
• Non-keratinised stratified squamous

  • Oval nuclei
  • protection/barrier
  • Found in oral cavity and oesophagus
• Simple cuboidal epithelium

  • Round nuclei
  • Secretion and absorption
  • Glands and kidney tubules
• Simple columnar epithelium

  • Basally located nuclei
  • Absorption and secretion
  • Gastrointestinal tract
  • Surface modification with microvilli (projection of the cytoplasm)
• Pseudostratified ciliated columnar epithelium

  • Appears stratified as some cells don't reach free surface
  • All cells touch basement membrane
  • Modification of cilia and goblet cells (unicellular)
  • Act as mucociliary escalator
  • Trachea and large respiratory airways
• Intercellular junctions

  *Specialised areas of cell membranes that bind one cell to another ● Examples:

  • Desmosomes: strong connection between adjacent cells, resist stretching and twisting
  • Hemidesmosomes: attaches cells to basement membrane, stabilises position and and anchors cell to underlying tissue
  • Tight junctions: interlocking proteins tightly bind cells together near apical edge. Prevents passage of H2O and solutes between cells
  • Gap junctions: cells held together by interlocking membrane proteins containing a central pore. Allows movement of small molecules and ions between cells
• Skeletal muscle (muscle cell)

  • Moves and stabilises the skeleton
  • Forms sphincter in the digestive and urinary tract
  • Long cylindrical cells
  • Striated
  • Multinucleated
  • innervated by somatic nervous system
• Smooth muscle (muscle cell)

  *walls of organs and blood vessels and airways - gastrointestinal muscles
• SMOOTH MUSCLE

  • located I walls or organs, blood vessels and airways
  • gastrointestinal movement
  • alters diameter of airways and blood vessels
  • short, fusiform cells, non-striated, single, centrally located nucleus
  • innervated by autonomic nervous system
• CARDIAC MUSCLE

  • found in heart wall
  • helps to circulate blood + maintain blood pressure
  • branched muscle fibres, striated, 1-2 central nuclei, intercalated discs
  • innovated by the autonomic nervous system