10.3- The five steps to infection Flashcards
Define Step 1 to infection
A pathogen must enter a host.
Define portal entry
Any site a pathogen may used to enter a host.
Name portals of entry
Ears, eyes, respiratory, GI, skin, urogenital/reproductive, parenternal (needles, bites, cuts, surgical incisions), transplacental (to unborn babies).
What is the most common port of entry for a pathogen?
The respiratory tract.
What port of entry demonstrates vertical transmission?
Transplacental entry
Define Step 2 to infection
Pathogen must adhere to host tissue.
Adhesin
A virulence factor that bacteria, fungi, protists, and viruses use to adhere to host tissue.
Define step 3 to infection
Pathogen most invade host cell tissue and obtain nutrients.
What are the three main options for pathogen invasion?
Remain on the surface
Reside in the cell
Invade deeper by passing through cells.
Sometimes they pass between cells too.
Define Siderophores
Iron binding complexes produced by bacteria to steal iron from transferrin- bacteria us it to steel iron from the host before it arrives at the host cell that needs it.
Step 4 to infection
Evade host cell immune defenses so it can reproduce.
How do pathogens hide?
They can change their antigen factors so they appear to something else, they can live within other cells so they aren’t identified by immune cells, or they can hide in biofilms.
Define antigen masking
Pathogen coats itself with host molecules letting it appear as part of the body.
Define antigenic mimicry
Emulating host molecules. Making capsules that resemble host cell carbohydrates.
Define antigenic variation
Periodically altering surface molecules that immune cells use to identify pathogens. I.E. Altering their genome so that different proteins result and are thus harder to identify.
