THE FIRST LINE OF DEFENCE The first line of defence is non-specific. The first line of defence is innate, that is, it is developed through birth. There is no specific response to any specific pathogen and no memory of the invading pathogen is created. The first line of defence includes physical and chemical barriers which prevent the entry of pathogens, facilitated on the surface of the body.
Physical barriers include:
· Intact skin – tightly packed cells form a tough and waterproof layer. The skin is also constantly shed
· Mucous membrane – line the inside of reproductive and respiratory tracts that are exposed to air
· Cilia – filter the air passing into the respiratory system
· Nasal hairs - filter the air passing through the nose
Chemical barriers include:
· Acids such as those found in urine, stomach to digest bacteria
· Enzymes found in saliva (amalyse) and tears (lysosomes) to digest bacteria
· Mucus - traps microorganisms and pathogens -Ear wax - wax substance secreted to protect the ear canal against bacteria and other substances and pathogens