Specialised Tissues

• Definitions

  • Tissues: Collection of cells similar to each other performing a common function
  • Animal tissue is grouped into 4 types:
  • Epithelial
  • Nervous
  • Muscle
  • Connective
  • Organs: Collection of tissues working together to perform a particular function
  • Systems: Number of organs working together to perform a life function
• Epithelial

  • Covers and protects internal and external body surfaces
  • Can be subdivided based on cell shape and function
  • Cuboidal epithelium
  • Aids absorption
  • Mechanical support
  • Columnar epithelium
  • Impermeable barrier to any ingested bacteria
  • Permeable to necessary ions
  • Simple squamous epithelium
  • Lines alveoli
  • Allows transport of small molecules over membrane
  • Stratified squamous epithelium
  • Protects areas subject to abrasion (e.g. skin)
  • Multi-layered
• Nervous

  • Made of neurones to conduct electrical impulses around body
• Muscle

  • Muscle cells:
  • ‘fibres’
  • Elongated
  • Contain myofilaments (made of actin and myosin)
  • Allow muscle tissue to contract
  • 3 types of muscle tissue (all well vascularised, lots of blood vessels)
  • Skeletal:
  • Joined to bones by tendons
  • When they contract, cause bones to move
  • Cardiac:
  • Makes up walls of the heart
  • Allows the heart to beat in a coordinated way
  • Smooth:
  • In walls of small intestine, blood vessels, uterus and urinary tracts
  • Propels substances along tracts
• Connective

  • Consists of non-living extracellular matrix containing proteins and polysaccharides
  • Separates living cells in tissue
  • Enables to withstand forces like mass
  • Widely distributed in body
  • In...
  • Bone (secretes calcium to harden)
  • Ligaments (connects bones, fibrous)
  • Blood (blood cells in fluid matrix, plasma)
  • Cartilage (protects bones by preventing them rubbing against each other)
• Cartilage

  • Immature Cells
  • Chondroblasts
  • Secrete extracellular matrix
  • Once matrix is synthesised, chondroblasts mature
  • Mature Cells
  • Chondrocytes
  • Less active
  • Maintain matrix
  • Cartilage has immature and mature cells, make 3 types
  • Hyaline cartilage:
  • Forms embryonic skeleton
  • Covers ends of long bones in adults
  • Joins ribs to sternum
  • In nose, trachea (C-Shaped), and larynx (voice box)
  • Fibrous cartilage:
  • In disks between vertebrae (spine)
  • In knee joint
  • Elastic cartilage:
  • Makes up outer ear and epiglottis