Chapter 2: Three lines of defense Flashcards
What are the three lines of defense?
1) Immediate innate
2) Induced innate
3) adaptive immunity
What is immediate innate?
Ready at all times
What is induced innate?
Few hours-4 days once cells recoginize presence of infection (slower than immediate innate but faster than adaptive)
What are intracellular pathogens?
Replicate inside human cells
Are intracellular pathogens killed by soluble secreted molecules? why or why not?
No because intracellular pathogens are not accessible to soluble secreted molecules.
How are intracellular pathogens killed?
By killing the human cell in which pathogen resides.
What are extracellular pathogens?
Pathogens that live and replicate in spaces between human cells
Are extracellular pathogens killed by killing the human cell next to the pathogen?
NO; the pathogen is outside the cell
How are extracellular pathogens killed?
By soluble secreted molecules.
For intracellular pathogens the human cell containing the pathogen is destroyed. How does this kill the pathogen?
The pathogen is now exposed to the soluble molecules of the immune system.
Describe how Influenza virus is both extracellular and an intracellular pathogen.
When particles of influenza virus first enter the respiratory tract they are extracellular and susceptible to attack by soluble molecules of the immune system. Once the viral particles have infected the epithelial cells that line the respiratory tract the influenza viruses is no longer an intracellular pathogen. At this stage in the viral life cycle, the infected cells can be recoginized and killed by effector cells of the immune system which detects virus-induced changes on the surface of the infected cell. With replication of the virus in the epithelial cell and the release of viral particles into the release of viral particles into the extracellular space, the virus again becomes a target for soluble effector molecules.
