Body defence against pathogens

• Skin acts as a barrier and prevents viruses and bacteria from reaching the tissue beneath
• When you cut your skin, platelets form and create a scab to prevent pathogens from entering the body
• Skin produces anti-microbial secretions to destroy pathogens
• Respiratory and digestive systems:

  • Nose hairs and mucus prevent pathogens from reaching the lungs
  • Trachea and bronchia have mucus trapping pathogens in the air
  • The lining of the tube has hair-like structures called Cilia that waft the mucus up the throat to be swallowed
  • Stomach acid destroys microorganisms in swallowed mucus and pathogens from drinking and eating
• Immune system:

  • White blood cells are the second line of defense when pathogens enter the body
• White blood cells ingest microorganisms, digest, and destroy them
• Some white blood cells produce antibodies to target specific pathogens for destruction
• Some white blood cells produce antitoxins to counteract toxins released by pathogens
• plants have 2 defence responses to pathogens: physical, bacterial.
• physical barriers of plants are; the cellulose wall(strengthen plant to make resistance to the entry of pathogens by piercing), the tough waxy cuticle on the surface (acts as a barrier against pathogens entering), bark on the trees(has a dead layer of cells protecting stems so no pathogens can penetrate it) and leaf fall (trees lose leaves in autumn to get rid of any diseases on them).
• chemical barriers of plants are: chemicals that kill pathogens, chemicals that repel pathogens