Defence Against Pathogens

Defence Against Pathogens

1. Animals

   • Skin
     • Physical barrier that blocks pathogens
     • Contains antimicrobial chemicals
   • Mucous Membranes
     • Protect body openings
     • Secrete mucous which traps and kills pathogens
   • Blood Clotting
     • Mesh of protein fibres
     • Prevent pathogen entry and blood loss
   • Inflammation
     • Tissue damage increases permeability of blood vessels
       • Leaks fluid into surrounding area and isolates the pathogens
       • Swelling
     • Vasodilation increases blood flow
       • More White blood cells
   • Wound Repair
     • Outer layers of skin divide and move to edge of wound
       • This tissue underneath contracts to connect the edges with collagen fibres
   • Expulsive Reflexes
     • Automatic response to expel foreign objects, including pathogens
     • Coughing and Sneezing

2. Plants

   • Physical
     • Waxy Cuticle
     • Cell walls
     • Callose Deposition
       • Sieve plate in the phloem are blocked by a polysaccharide called callose. This prevents pathogens from moving through the phloem
   • Chemical
     • Produce antimicrobial chemicals
       • Saponins
     • Chemicals that are toxic to insects