Innate Immunity

Question 1

What 3 factors determine the outcome of the host-pathogen relationship

One of these factors is lower for 3 groups of people, what are these 3 groups?

Answer 1

Infectivity of pathogen (Ability to establish on/ in the host)

Host’s immune response (Lower for Infants, Elderly, Pregnants)

Virulence (Capability of pathogen to damage host)

Question 2

What are 4 roles of the immune system

Answer 2

• Pathogen recognition
• Containing/ eliminating the infection
• Regulating itself
• Remembering pathogens

Question 3

Compare the 2 components of the immune response

Which is most important for human survivial

Answer 3

Innate immunity

• Fast (Seconds)
• Lack of specificity
• Lack of memory
• No intensity change

Adaptive immunity= Most important

• Slow (Days)
• Specific
• Immunologic memory
• Changes in intensity

Question 4

What are the 4 innate barriers

Answer 4

Physical
Physiological
Chemical
Biological

Question 5

Name 3 physical barriers

Answer 5

Skin
Mucosal membranes
Bronchial Cilia

Question 6

Name 4 physiological barriers

Answer 6

Diarrhoea
Vomiting
Coughing
Sneezing

Question 7

Name 2 chemical barriers

Answer 7

Low pH

Antimicrobial molecules

Question 8

Name 1 Biological barrier
Where are they absent

Outline 3 benefits

Answer 8

Normal flora is absent in internal organs/ tissues

• Compete with pathogens for resources and attachment sites
• Produce vitamins
• Produce Antimicrobial chemicals

Question 9

State 6 ways clinical problems start due to Normal flora

Answer 9

• Skin integrity broken
• Fecal oral route
• Fecal perineal urethral route
• Poor dental hygiene/ work
• Normal flora overgrows and becomes pathogenic when host is immuno-compromised
• Normal flora in muscles all surfaces is depleted by antibiotics

Question 10

What does the spleen do

Answer 10

Protects against microbes in blood

Question 11

Give 2 examples of Normal flora depletion by antibiotics, that leads to clinical problems

Answer 11

In intestine, Colitis arises from Clostridum Difficile

In vagina, Thrush arises from Candida Albicans

Question 12

Innate barriers the first lines of defence
What are 2 examples of the second lines of defence

What do they result in

Answer 12

Phagocytes
Chemicals

Inflammation

Question 13

What do Macrophages release

Answer 13

Cytokines and Chemokines

Question 14

How are pathogens recognised by phagocytes

Answer 14

PRRs (Pathogen Recognition Receptors) on Phagocytes binds PAMPs on Pathogens

Question 15

What PRR recognises Lipopolysaccharide (LPS)

Answer 15

TLR4

Question 16

What are opsonins

Answer 16

Coating proteins that bind to microbial surfaces, leading to enhanced attachment of phagocytes

Question 17

What does PAMP to PRR binding cause

What does Opsonin to Opsonin receptor binding cause

Answer 17

PAMP-PRR: Signal to produce chemokines and cytokines

O-OR: Causes phagocytosis

Question 18

Name the 2 phagocyte intracellular killing mechanisms

Answer 18

1. Oxygen-dependent pathway (Respiratory burst)

2. Oxygen-independent pathways

Question 19

What are the actions of complement proteins;

1. C3a and C5a
2. C3b-C4b
3. C5-C9

Answer 19

1. Phagocyte recruitment
2. Opsonisation of pathogens
3. Killing of pathogens, Membrane Attack complex

Question 20

What 3 functions are carried out by Cyto/ Chemo-kines

Answer 20

1. Chemoattraction
2. Phagocyte activation
3. Inflammation

Question 21

What Are 3 systemic and 1 local inflammatory actions of the cytokines IL-1, IL-6 and TNF-Alpha

Answer 21

Systemic:

• CRP Released from liver
• Neutrophil mobilisation in bone marrow
• Increased body temp. In hypothalamus

Local:

• Blood vessels dilate, so increased permeability, so attraction of neutrophils as adhesion molecules are expressed