M6-Immunology and Host-Pathogen Interactions

Question 1

What is immunity?

Answer 1

Ability to resist infectious disease

Question 2

What does the immune system comprise?

Answer 2

• Cells
• Organs
• Secreted factors

Question 3

What does the immune system do?

Answer 3

• Control pathogens that enter the body and caners
• Maintain a healthy relationship with the normal microbiome at the body surface

Question 4

What are the different types of pathogens?

Answer 4

• Viruses: few molecules, replicate within cells, rapid evolution
• Bacteria: can live in extracellular space, or within phagosomes/cytoplasm
• Large parasites: live within body fluids or gut
• Unicellular eukaryotic parasites: frequently live inside cells

Question 5

Under what condition can a pathogen be attacked directly?

Answer 5

If a pathogen lives in extracellular fluid, bacteria can be phagocytosed

-But large multicellular organisms cannot

Question 6

If a pathogen is within cells, how can it be attacked?

Answer 6

• Immune system must attack the infected cell, or
• Induce changes in the cell to kill invader

Question 7

What are the mechanisms of prevention of infection?

Answer 7

1. Physical and chemical barriers to pathogen invasion
2. Active defence by innate immune cells
3. Active defence by cells of the acquired immune system