entry-routes-of-pathogens

Entry Routes of Pathogens

• In order for pathogens to cause disease they need to enter the body

• There are four main ways in which pathogens can enter

  • Broken skin

    • This provides direct access to the tissues and bloodstream

  • The digestive system

    • When we consume contaminated food and drink

  • The respiratory system

    • Every time we inhale

  • Mucosal surfaces

    • The lining of body cavities e.g. inside of nose, mouth, genitals

Barriers to infection

• Skin

  • This provides a physical barrier against infection

  • If the skin is damaged it leaves the exposed tissue beneath vulnerable to pathogens

  • The blood clotting mechanism of the body plays an important role in preventing pathogen entry in the case of damage to the skin

  • Blood clotting takes time, however, so a few pathogens may still enter before a clot forms

• Microorganisms of the gut and skin

  • Collectively these harmless microorganisms are known as the gut or skin flora

  • They compete with pathogens for resources, thereby limiting their numbers and therefore their ability to infect the body

• Stomach acid

  • The hydrochloric acid that makes up a large part of the gastric juices in the stomach creates an acidic environment that is unfavourable to many pathogens present on food and drink

  • Sometimes a few of these pathogens may survive and make their way to the intestines where they infect the gut wall cells and cause disease

• Lysozyme

  • Secretions of the mucosal surfaces, e.g. tears, saliva, and mucus, contains an enzyme called lysozyme

  • This enzyme will damage bacterial cell walls, causing them to burst, or lyse

The body has physical defences that prevent the entry of pathogens