Primary non specific defences in animals Flashcards
What are non-specific defences?
first line of defence that can often prevent infections from fully entering the body
What does ‘non-specific’ mean?
defend against a wide range of potential pathogens
What are the 8 non-specific defences?
-inflammation
-blood clotting
-mucous membranes
-wound repair
-expulsive reflexes
-lysozyme action
-interferon
-phagocytosis
2 ways that inflammation is a defence
-injured tissue releases molecules to increase permeability so pathogens are isolated and swelling occurs
-cause blood vessels to widen, blood flow increases so WBCs arrive to fight pathogens
What triggers inflammation?
tissue damage
What is the term for widening of blood vessels
vasodilation
How are blood clots a defence?
mesh of protein fibres plug wounds to prevent pathogen entry and blood loss
How are mucous membranes a defence? (2)
-protect body openings that are exposed to environment
-can secrete sticky mucus to trap pathogens
How is wound repair a defence?
Skin can divide and migrate to edges of wound, tissue beneath contracts to bring edges of wound closer to reform barrier
What fibres help repair wounds?
collagen fibres
How are expulsive reflexes a defence?
expelling foreign objects, including pathogens, from body
2 examples of expulsive reflexes
-sneezing when dust/dirt irritates mucous membranes in nostrils
-coughing due to irritation in respiratory tract
How are lysozymes a defence?
enzyme found in secretions such as tears/mucus, kills bacterial cells by damaging their cell wall
How is interferon a defence?
prevents viruses spreading to uninfected cells by stopping protein synthesis in viruses
How is phagocytosis a defence?
WBCs engulf pathogens and destroy them by fusing a pathogen in a phagocytic vacuole with a lysosome
