EXTERNAL DEFENCE SYSTEM of body
Epithelial Barriers
Role of Skin
Role of Mucous Membrane
Role of Body Secretions
Skin consists of Keratin which is impermeable to most of the microbes.
Most Bacteria fail to survive on skin because of the inhibitory effect of saturated and unsaturated fatty acid.
Acidic pH of skin prevents growth of bacteria.
ROLES OF MUCOUS MEMBRANE
It secretes mucus which is a protective barrier.
Mucous secretion - contains Lysozyme which kills bacteria. Lysozyme and Γ defensins are antibacterial peptides.
ROLES OF BODY SECRETION
Skin secretion like sweat and sebum contain Bactericidal Substances.
Tears also contains Lysozyme.
Mucopolysacchrides in saliva inactivate bacteria and Virus.
Gastric juice contains HCl which keeps Stomach free from microbes.
INTERNAL DEFENCE
It includes:-
- When infective agent penetrates body by passing the barriers of external defense the tissue factors comes into play.
-TYPES:-
Humoral factors
Lysozyme
Complement
Properdin
Interferon
Phagocytin
Other microbial substances
Microphages
Macrophages
Natural killer cells
Large granular lymphocytes
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