Lecture 2: Immune Function

Question 1

What are the 3 lines of defense body uses to defend itself against foreign invaders?

Answer 1

1st: Barrier (skin)
2nd: Innate (WBC)
3rd: Adaptive (IgG)

Question 2

What are the characteristics of Barrier Defenses?

Answer 2

Don’t specify between microbes

-Can be breached (cuts, ingestion, inhalation)

Question 3

What are the characteristics of Innate immunity?

Answer 3

• Rapid
• Nonspecific
• Leukocytes (phagocytes) like WBC’s eat pathogens
• Mainly to hold off pathogen until adaptive immunity kicks in

Question 4

What are the characteristics of Adaptive Immunity?

Answer 4

• Slow
• Highly specific
• Very effective
• Develops response for specific type of pathogen

Question 5

What is the goal of a pathogen? What is the problem? What is the solution?

Answer 5

Goal of pathogen is to reproduce

• Too successful = kill host
• Not successful = kill pathogen

Solution is co-evolution.
-Balanced relationship

Question 6

What is an example of the co-evolution of pathogen/host?

Answer 6

Seasonal Flu

• Population develops adaptive immunity to strain during flu season
• Virus mutation creates new strain
• The population will have partial protection

Question 7

Microbes evolve faster than humans. What problem does this create?

Answer 7

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

Question 8

What is a PAMP?

Answer 8

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

Question 9

What is an Antigen?

Answer 9

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

Question 10

How do we recognize and differentiate different pathogens?

Answer 10

PAMPs and Antigens

Question 11

What is the difference between extracellular and intracellular pathogens?

Answer 11

Extracellular

• Colonize surfaces
• Circulate in fluids
• Replicate outside of host

Intracellular

• Invade host cells
• Replicate within host

Question 12

What are the types of extracellular and intracellular pathogens?

Answer 12

Extracellular
-Bacteria, Fungi, and Parasites

Intracellular
-Viruses

Question 13

What are characteristics of bacteria pathogens?

Answer 13

Simple
Unicellular
Prokaryotic (No nucleus)

Question 14

How do bacterial cell walls differ?

Answer 14

Peptidoglycan

Gram Positive
-Thick with Peptidoglycan

Gram Negative

• Thin with little peptidoglycan
• Produce Lipopolysaccharides which is a PAMP

Question 15

Are bacteria extracellular or intracellular or both?

Answer 15

Both

-Most exist as extracellular pathogens but some reproduce as intracellular

Question 16

What are the characteristics of Fungi pathogens?

Answer 16

Complex, unicellular, eukaryotic (true nucleus)

-Most are extracellular pathogens

Question 17

What are the characteristics of Parasite pathogens?

Answer 17

Most are extracellular

Two Types:

1) Unicellular Eukaryotic microbes (protozoa)
2) Multicellular Eukaryotic animals (helminths)

Question 18

What are the characteristics of viruses?

Answer 18

Acellular infectious particles

• Nucleic acid genome (dsRNA PAMP)
• Protein coat (antigen)
• Obligate intracellular (host needed for repro)

Question 19

How do PRRs and PAMPs work as part of innate immunity ?

Answer 19

Recognize harmful vs nonharmful

• Pattern recognition Receptors (PRR) detect Pathogen associated Molecular Patterns (PAMP)
• The cell will release Cytokines which trigger inflammatory response

Question 20

How do cytokines help immune reponse?

Answer 20

Cytokines signal immune response

• Results in increased blood flow to site of infection
• Gets more WBC’s to site

Question 21

How do Antigens and Antigen receptors work as part of the adaptive immune system?

Answer 21

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

Question 22

Development, Surveillance, Recruitment, and Elimination are the steps of the immune response. Explain.

Answer 22

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