Non-specific Body Defences Flashcards Preview

Higher Human Biology - Unit 3 > Non-specific Body Defences > Flashcards

Flashcards in Non-specific Body Defences Deck (4)
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What is a physical defence?

Closely packed epithelial cells found on the surface of skin and lining the body's digestive and respiratory system offer a physical barrier against bacteria and viruses


What is a chemical defence?

Secretions including tears, saliva, mucus and stomach acid are produced against invading pathogens (disease causing microorganism)


An inflammatory response is caused by what?

By a physical injury such as a cut or invasion of microorganisms

Following injury, mast cells found in the connective tissue become activated releasing large quantitates of histamine, a chemical which causes vasodilation and capillaries to become more permeable

The increased blood flow leads to accumulation of phagocytes and clotting elements at the site of infection


What do phagocytes do?

They recognize pathogens, engulf them and destroy them using digestive enzymes contained in lysosomes through phagocytosis

They also release cytokines (protein molecules which act as a signal) attracting more phagocytes to area of infection