Lecture 42

Question 1

What are the benefits of inflammation?

Answer 1

• rapid migration of phagocytes to the site of injury

- higher set point of core body temp —> activates phagocytic cells & inhibits growth of bacteria

Question 2

What are the steps that occur during inflammation ?

1) Inflammation mediators released

Answer 2

Inflammation mediators are released from macrophages, dendritic cells and mast cells upon tissue damage
——> triggers release of cytokines

Question 3

What are the steps that occur during inflammation?

2) Effects of inflammation mediators

Answer 3

• capillary vasodilaiton - histamines
• vascular permeability of blood vessel “sticky”
• —-> by leukotrienes and prostaglandins

Question 4

Cytokines are released by macrophages, mast cells and dendritic cells upon pathogenic invasion.

What effect do cytokines have on the liver?

Answer 4

• Haptoglobin released
• –> takes up iron - prevents uptake by bacteria
• Fibrinogen
• –> involved in clot formation - traps bacteria in clot - prevents spread of infection

Question 5

What effect do cytokines have on the brain?

Answer 5

Causes pyrexia –> interleukin 1 increased body temp, effects the hypothalamus

Question 6

What effects do cytokines have on bone marrow?

Answer 6

• increases production of neutrophils
  neutrophils migrate to to site of infection, stick to blood walls & enter infected tissue through diapedesis
  –> neutrophils digest bacteria & become puss cells, have a high turnover

Question 7

What are toll-like receptors ?

- non specific receptors of the innate immune system

Answer 7

Pattern recognition receptor that distinguishes foreign cells from its own —-> detects microbes by interacting with component that our cells do not have

• found on plasma membrane
  e. g flagella, cell wall

Question 8

What is an example of a TLR?

Answer 8

TL2 - detects gram postive

TL4 - detects gram negative

Question 9

What are the stages of phagocytosis?

Answer 9

• Pseudopodia formation
• Adherence
• Ingestion
• fusion of lysosome and vacuole
• Killing and digesting
• Elimination - exocytosis

Question 10

What are the three complement pathways?

Answer 10

• Classical = antibody binds with antigen Ab-Antigen complex - adaptive as antibody needs to be made Ist
• Alternative = complement binds to pathogen
• Lectin = complement binds to lectin

Question 11

The activation of one of the three pathways triggers the complement cascasde what are the 3 outcomes?

Answer 11

Opsonisation = coating microbes w C3a or antibody

Recruitment = phagocytes are attracted to site
mast cells degranulates by C3a or C5a which enhances inflammatory response and attracts phagocytes

Destruction - Lysis - opsonised microbes are phagocytosed
- assemble of MAC complex C9 forms pores in the membrane of bacterial

Question 12

How do pathogens evade the innate immune system?

Answer 12

• capsule - increases phagocytosis resistance
• making surface molecules that resist antimicrobial peptides
• prevent fusion of phagocytes and lysosome