2' Nonspecific defense mechanism

1
2. Non-specific defense mechanism

• Physical barriers
• Skin (stratified squamous epithelium of
  epidermis)
• Mucous membranes of the respiratory tract
• Form a natural physical barrier
• Prevent the entry of pathogens
• The first line of defense

2

• Chemical barriers

• Gastric juice in stomach -- powerful sterilizing
  liquid
• Lysozyme in tissue fluids -- lyse many bacteria

3

• Phagocytosis

• Eating process
• Phagosome surrounds the pathogen
• Lysosomes fuse with the phagosome to digest and
  destroy the pathogen
• Residues discharged out of the cell

4

• Inflammatory Response

• Large number of phagocytes are attracted to the
  wound area
• Eat and kill the pathogens

5

• Blood vessels dilate
• ? Blood flow to the area increases
• ? Massive flow of fluids out from the
  blood into the tissues
• ? Swelling
• Phagocytes move out from the blood into the area
• Functions of blood clotting
• Prevent loss of blood
• Prevent entry of bacteria and fungi