non-specific body defences 3.5 Flashcards
the immune system
the body’s way of defending itself against disease causing organisms (pathogens), some toxins (poisons produced by living things) and cancer cells
what is immunity
the ability for the body to resist infection by a pathogen or destroy an organism if it invaded and infects the body
what is a pathogen
a bacterium, virus or other organism that can cause disease
how many lines of defence does the body have
three
what does bodies first line of defence do
it prevents pathogens causing diseases
what does the bodies first line of defence consist of
a physical barrier and chemical secretions
a physical barrier
made up of closely packed epithelial cells which can be found in the skin as well as the inner linings of the digestive and respiratory systems
chemical secretions
including tears, saliva, mucus and stomach acid that are produced against invading pathogens
when does the inflammatory response occur
when pathogens get past our first lines of defence and enter our body
inflammatory response
histamine is released by mast cells causing vasodilation and increased capillary permeability
what does the increased blood flow cause
the accumulation of phagocytes and clotting enzymes at the site of infection
what are phagocytes
a type of white blood cell that recognises pathogens and destroys them by phagocytosis
phagocytosis
involves the engulfing of pathogens and their destruction by digestive enzymes containing lysosomes
what do phagocytes release during phagocytosis
cytokines which are a type of protein molecule that acts as a signal to attract more phagocytes and specific blood cells causing them to accumulate at the site of infection
