Lecture 2: Immune Function Flashcards
What are the 3 lines of defense body uses to defend itself against foreign invaders?
1st: Barrier (skin)
2nd: Innate (WBC)
3rd: Adaptive (IgG)
What are the characteristics of Barrier Defenses?
Don’t specify between microbes
-Can be breached (cuts, ingestion, inhalation)
What are the characteristics of Innate immunity?
- Rapid
- Nonspecific
- Leukocytes (phagocytes) like WBC’s eat pathogens
- Mainly to hold off pathogen until adaptive immunity kicks in
What are the characteristics of Adaptive Immunity?
- Slow
- Highly specific
- Very effective
- Develops response for specific type of pathogen
What is the goal of a pathogen? What is the problem? What is the solution?
Goal of pathogen is to reproduce
- Too successful = kill host
- Not successful = kill pathogen
Solution is co-evolution.
-Balanced relationship
What is an example of the co-evolution of pathogen/host?
Seasonal Flu
- Population develops adaptive immunity to strain during flu season
- Virus mutation creates new strain
- The population will have partial protection
Microbes evolve faster than humans. What problem does this create?
Newly introduced microbes, that the population has not been exposed to, cause MORE SEVERE disease
- We have no immunity and can’t evolve fast enough
- This results in more death before adaptive response
What is a PAMP?
Pathogen-Associated Molecular Pattern
- Conserved molecules of related microbes that are recognized by INNATE immune cells
- More general
- Looks for similar microbes that are DANGEROUS & FOREIGN
What is an Antigen?
Specific Molecules that differentiate microbes and are recognized by ADAPTIVE immune cells
- Most antigens recognized by adaptive immune cells are proteins
- Key & Lock mechanism
- Looks for FOREIGN microbes only
How do we recognize and differentiate different pathogens?
PAMPs and Antigens
What is the difference between extracellular and intracellular pathogens?
Extracellular
- Colonize surfaces
- Circulate in fluids
- Replicate outside of host
Intracellular
- Invade host cells
- Replicate within host
What are the types of extracellular and intracellular pathogens?
Extracellular
-Bacteria, Fungi, and Parasites
Intracellular
-Viruses
What are characteristics of bacteria pathogens?
Simple
Unicellular
Prokaryotic (No nucleus)
How do bacterial cell walls differ?
Peptidoglycan
Gram Positive
-Thick with Peptidoglycan
Gram Negative
- Thin with little peptidoglycan
- Produce Lipopolysaccharides which is a PAMP
Are bacteria extracellular or intracellular or both?
Both
-Most exist as extracellular pathogens but some reproduce as intracellular
What are the characteristics of Fungi pathogens?
Complex, unicellular, eukaryotic (true nucleus)
-Most are extracellular pathogens
What are the characteristics of Parasite pathogens?
Most are extracellular
Two Types:
1) Unicellular Eukaryotic microbes (protozoa)
2) Multicellular Eukaryotic animals (helminths)
What are the characteristics of viruses?
Acellular infectious particles
- Nucleic acid genome (dsRNA PAMP)
- Protein coat (antigen)
- Obligate intracellular (host needed for repro)
How do PRRs and PAMPs work as part of innate immunity ?
Recognize harmful vs nonharmful
- Pattern recognition Receptors (PRR) detect Pathogen associated Molecular Patterns (PAMP)
- The cell will release Cytokines which trigger inflammatory response
How do cytokines help immune reponse?
Cytokines signal immune response
- Results in increased blood flow to site of infection
- Gets more WBC’s to site
How do Antigens and Antigen receptors work as part of the adaptive immune system?
B-cell Receptors (BCR) and T-cell Receptors (TCR) will bind to an antigen
- Helper Tcell will transmit a chemical signal
- Becomes Plasma cell and releases antibodies
Development, Surveillance, Recruitment, and Elimination are the steps of the immune response. Explain.
Development
- Immune Cells develop/mature in the bone marrow
- T Cells mature in the thymus
Surveillance
-Immune cells patrol the body
Recruitment
-When immune cells find trouble they use cytokines to recruit others to fight
Elimination
-Effector cells used to kill the infection
