communicable diseases #7: Non-specific human defence systems against disease Flashcards
what are the first lines of defence against disease? (4)
skin, nose, trachea and bronchi, stomach
how does the skin defend?
If it is cut or grazed it immediately begins to heal itself, often by forming a scab, which prevents infection as the scab acts as a physical barrier.
what about parts of the body that do not have skin? (eyes)
eyes have tears which contain enzymes and these are chemical barriers.
how does the nose defend?
it has internal hairs, which act as a physical barrier to infection. Cells in the nose produce mucus. This traps pathogens before they can enter the lungs. When the nose is blown, mucus is removed and any pathogens are trapped within it.
how does the trachea and bronchi defend?
trachea has ciliated cells waft their hairs and move mucus and pathogens upwards towards the throat where it is swallowed into your stomach. Other cells called goblet cells create the mucus in order to trap pathogens. The production of mucus in your airways is a physical barrier.
how does the stomach defend?
the hydrochloric acid inside the stomach is strong enough to kill any pathogens that have been caught in mucus in the airways or consumed in food or water. Stomach acid is a chemical barrier against infection.
