Chapter: Tissues

• Introduction

  • Definition of Tissue
  • Division of labour in multicellular organisms
  • Plant vs. Animal tissues (based on mobility and energy needs)

• Plant Tissues

  • Meristematic Tissues (Actively dividing cells)
    • Apical meristem (Root and shoot tips - increases length)
    • Intercalary meristem (At internodes/base of leaves - increases length)
    • Lateral meristem (Cambium - increases girth/thickness)
    • Features: Dense cytoplasm, thin walls, prominent nuclei, no vacuoles
  • Permanent Tissues (Derived from meristematic, lost ability to divide)
    • Simple Permanent Tissues (Single type of cells)
      • Parenchyma (Living, stores food, has intercellular spaces)
        • Chlorenchyma (Contains chlorophyll, does photosynthesis)
        • Aerenchyma (Has air cavities, provides buoyancy in aquatic plants)
      • Collenchyma (Living, unevenly thick corners, provides flexibility/bending)
      • Sclerenchyma (Dead, thick lignified walls, provides mechanical strength, e.g., coconut husk)
    • Complex Permanent Tissues (More than one type of cells, transport)
      • Xylem (Transports water and minerals upwards)
        • Tracheods
        • Vessels
        • Xylem parenchyma
        • Xylem fibres
      • Phloem (Transports food from leaves to other parts)
        • Sieve tubes
        • Companion cells
        • Phloem parenchyma
        • Phloem fibres

• Animal Tissues

  • Epithelial Tissue (Covering and protective tissue)
    • Squamous (Thin, flat, delicate - lining of blood vessels, lung alveoli)
    • Cuboidal (Cube-like - kidney tubules, salivary gland ducts)
    • Columnar (Pillar-like, absorptive - lining of intestine, respiratory tract with cilia)
    • Glandular (Infolded epithelial cells for secretion)
  • Connective Tissue (Binding, supporting, transporting)
    • Blood (Fluid matrix/plasma with RBCs, WBCs, platelets - transports gases/nutrients)
    • Bone (Hard, porous matrix of calcium and phosphorus - supports body)
    • Ligaments (Connects bone to bone - elastic)
    • Tendons (Connects bone to muscle - fibrous, less elastic)
    • Cartilage (Solid flexible matrix - ear, nose, trachea joints)
    • Areolar (Loose connective tissue - fills space inside organs, fixes skin)
    • Adipose (Fat-storing tissue - beneath skin, insulating layer)
  • Muscular Tissue (Movement and locomotion)
    • Striated / Skeletal / Voluntary (Long, cylindrical, multinucleated, striped)
    • Smooth / Unstriated / Involuntary (Spindle-shaped, uninucleated - stomach, blood vessels)
    • Cardiac / Heart Muscle (Cylindrical, branched, uninucleated, involuntary, rhythmic contraction)
  • Nervous Tissue (Control and coordination, impulse transmission)
    • Neuron structure
      • Cell body (Cyton)
      • Dendrites (Short branched branches)
      • Axon (Long tail-like nerve fiber)
      • Nerve endings