Innate Immunity II

Question 1

What is the first stage of the inflammatory response?

Answer 1

Chemical signals from tissue-resident cells act to attract more cells to the site of injury or infection

Question 2

What is the second stage of the inflammatory response?

Answer 2

Neutrophils enter blood from bone marrow
Fast process

Question 3

What is the third stage of the inflammatory response?

Answer 3

Neutrophils cling to the capillary wall
Slows neutrophil down and directs it to target

Question 4

What is the fourth stage of the inflammatory response?

Answer 4

Chemical signals from tissue-resident cells dilate blood vessels and make capillaries ‘leakier’
More dilation = more blood flow into site of infection

Question 5

What is the fifth stage of the inflammatory response?

Answer 5

Neutrophils squeeze through the leaky capillary wall and follow the chemical trail to the injury site causing the tissue to swell

Question 6

What is the first stage of phagocytosis?

Answer 6

Phagocyte adheres/binds to pathogen or debris

Question 7

What is the second stage of phagocytosis?

Answer 7

Phagocyte forms pseudopods that eventually engulf the particles forming a phagosome

Question 8

What is the third stage of phagocytosis?

Answer 8

Lysosome fuses with the phagocytic vesicle forming a phagolysosome

Question 9

What is the fourth stage of phagocytosis?

Answer 9

Toxic compounds from lysosome and lysosomal enzymes destroy pathogens

Question 10

What is the fifth stage of phagocytosis?

Answer 10

Sometimes exocytosis of the vesicle removes indigestible and residual material

Question 11

How are phagocytoses microbes killed?

Answer 11

Low pH environment is unfavourable for bacteria
Reactive oxygen and nitrogen intermediate are very toxic
Enzymes engulf microbes

Question 12

What is the complement cascade?

Answer 12

9 major proteins/protein complexes act in sequence to clear pathogens from blood and tissues

Question 13

What is the classical complement pathway?

Answer 13

Antibody bound to pathogen binds complement
Adaptive and innate immune system work together

Question 14

What is the alternative complement pathway?

Answer 14

Pathogen binds complement to surface/pathogen component
Does not need adaptive immune response

Question 15

What is the lectin complement pathway?

Answer 15

Carbohydrate components of microbes bind complement
Does not need adaptive immune response

Question 16

What are the three outcomes from the complement cascade?

Answer 16

Label
Destroy
Recruit

Question 17

What is the ‘label’ outcome?

Answer 17

Opsonisation - labels pathogens which bind to complement receptors on phagocytes
Coats microbe with antibody or complement fragment C3b

Question 18

What is the ‘rapid’ outcome?

Answer 18

Membrane attack component (MAC), complex formation pores in bacterial cells -> death
Inflammatory mediators released including proteins that attract phagocytes

Question 19

What is the ‘destroy’ outcome?

Answer 19

Complement proteins act as peptide mediators of inflammation and recruit phagocytes
Microbes coated with C3b are phagocytosied
Assembly of MAC causes lysis