6.2.2 - Entry Routes Of Pathogens Flashcards
How Do Pathogens Cause Disease?
By entering the body.
How Can Pathogens Enter The Body?
(4 Points)
~ Through cuts in the skin, providing direct access to tissues and the bloodstream.
~ Through the digestive system via contaminated food or drink.
~ Through the respiratory system, when inhaled.
~ Through mucosal surfaces. E.g. Nose, mouth and genitals.
What Are All The Barriers That Prevent Infection?
(4 Points)
~ Stomach acid.
~ Skin.
~ Gut and skin flora.
~ Lysozyme.
Describe ‘Stomach Acid’ As A Barrier Preventing Infection
(3 Points)
~ Concerned with consumption of food and drink mainly.
~ Contains hydrochloric acid, creating an acidic environment which is unfavourable to many pathogens.
~ Some pathogens may survive and pass into the intestines, where they can infect cells of the gut wall and cause disease.
Describe ‘Skin’ As A Barrier Preventing Infection
(3 Points)
~ Provides a physical barrier against pathogens.
~ If damaged, leaves exposure to pathogens to tissues and the bloodstream.
~ Blood clots in the damaged area prevent entry to pathogens, but takes time to form allowing some pathogens to enter.
Describe ‘Gut & Skin Flora’ As A Barrier Preventing Infection
(3 Points)
~ The intestines and skin are covered with microorganisms called ‘flora’.
~ They compete with pathogens for nutrients and space.
~ Limiting the number of pathogens in the gut and skin, making it harder to infect the body.
Describe ‘Lysozyme’ As A Barrier Preventing Infection
(2 Points)
~ Mucosal surfaces produce secretions such as tears, saliva and mucus which all contain the enzyme lysozyme.
~ Lysozyme kills bacteria by damaging their cell walls, causing them to burst open (Lyse).