Section 5 Flashcards
What are characteristics of a surface infection?
- Multiply in epithelial cells at site of entry
- Can spread to other area
- Large area of body may be covered
- Innate immune system involved
Do surface infections penetrate deeper tissues?
No
Why is only the innate immune system involved in surface infections?
Not enough time for adaptive response
What are characteristics of systemic infections?
- Shed via blood/lymph
- Migrate from surface to deeper tissue
Why do systemic infections migrate?
Because they are enduring an increased immune repsonse
What are factors that affect the location of infections?
- Temperature
- Budding
- Systemic spread
What are examples of pathogens that are sensitive to temperature?
- Rhinovirus
- Mycobacterium leprae
What are examples of pathogens that experience budding?
Influenza and parainfluenza viruses
Where are the influenza and parainfluenza viruses released from?
Lung epithelial cells
What is the site of primary infection for measles and does it replicate there?
- Respiratory tract
- No
What is the site of primary infection for typhoid and does it replicate there?
- GI tract
- No
What is the site of primary infection for HAV and where does it spread to?
- Alimentary canal
- Liver
What is the site of primary infection for mumps and where does it spread to?
- Respiratory tract
- Salivary glands
How can pathogens avoid destruction in the blood?
- Localization at less well-defended sites
What does a pathogen encounter if it is free in blood?
Abs and phagocytes
How can a pathogen avoid Abs and phagocytes and what are examples of pathogens that do this?
- If it is associated with circulating cells in the bloodstream
- Ebola, rubella, listeria
What type of pathogens spread via nerves?
Viruses
How do viruses travel via nerves?
From peripheral nerves to CNS via axons and vice versa
What is the most important factor in CNS infections?
Crossing the blood-brain barrier
What is the disadvantage to the blood-brain barrier?
It keeps pathogens out, but it also keeps immune cells out
What are characteristics of the ideal Ab to treat CNS infections?
Small and hydrophobic
How can microbes spread from one visceral organ to another?
Through the peritoneal or pleural cavity
What determines if a pathogen has a narrow or broad host range?
Number of receptors on different species
What is an example of a pathogen that has a narrow host range and what does its range include?
- Measles
- Humans and closely-related primates
