Successful immunity in vertebrates leads to ___ , but in invertebrates, they soon are ___ again
Immune memory, susceptible
Primitive method of immunizing people against smallpox, using dried and powdered smallpox scabs administered intranasally or into cuts on the arm
Variolation (dangerous, 1-2% mortality)
Vaccine types
Attenuated - living (but weak virus) eg. cow pox
Inactivated - killed whole pathogen (components of virus still intact)
Subunit - parts of pathogen
4 types of pathogens
Virus, fungus, parasite, bacterium
Advantages of cowpox variolation over smallpox variolation
Milder symptoms, no mortalities, while conferring the same benefits as smallpox variolation (immunity)
Immune ‘priming’ in response to vaccine leads to immune memory that protects against the infecting pathogen is the result of
Vaccination
Vaccination risk (1) and what is it thought to be caused by
Anaphylaxis - thought to be caused by vaccine quality or handling errors
The number of new infections caused by each infected person in a population with no immunity
Reproduction ratio (Ro)
An Ro > 1 is an:
Epidemic - the infection will spread
The proportion of a population that needs to be immune (via. infection or vaccination) to prevent pathogen spread
Herd immunity *1 - 1/Ro
The more easily transmitted the pathogen, the ___ the population proportion that needs to be immunized to achieve herd immunity
Higher/greater
Viral entry routes (5)
Respiratory tract, GI (alimentary) tract, urogenital tract, skin (scratches, insect bites), conjunctiva (mucous membrane that covers the eyes)
Physical barriers to infection
Skin, mucus (traps microbes), mucous membranes
Chemical barriers to infection (4)
Enzymes (mucus, tears, saliva)
Acid (sweat, stomach)
Anti-bacterial proteins and zinc (in semen)
Anti-microbial peptides (throughout human body)
What cell secretes mucus
Goblet cells
Ciliated epithelial cells in the trachea and nasopharynx push mucus in the airways up to the throat, where the bacteria that are trapped with the mucus are coughed out or swallowed
Ciliary escalator
Biological barriers to infection
Immune system, normal microbial flora
How do normal flora help prevent infection
Occupation of habitat, competition for resources
What screens the blood for pathogens?
What screens the body tissues?
Spleen, lymph nodes (contain immune cells)
