Enzyme Cascade Systems

Question 1

what are the 4 main cascade systems?

Answer 1

blood clotting, kinin system, fibrinolytic system and complement system

Question 2

what responses does the complement system enhance?

Answer 2

phagocytosis, cytolysis and inflammation

Question 3

what is the alternate pathway?

Answer 3

non specific response, most recently discovered

Question 4

what is the classical pathway?

Answer 4

specific response so requires antibodies

Question 5

what is the lectin pathway?

Answer 5

similar to classical, mannose-binding lectin recognises carbohydrate tags on pathogens to activate complement

Question 6

what do complements exist as before being activated?

Answer 6

proenxymes in the blood

Question 7

how does the alternative pathway begin?

Answer 7

C3 becomes activated to become C3a and C3b

Question 8

what is C3 activated by?

Answer 8

a molecule from the bacteria

Question 9

what does C3b do?

Answer 9

sticks to the bacteria cell surface and activates C5

Question 10

what does activated C5 do?

Answer 10

splits into C5a and C5b

Question 11

how does the membrane attack complex form?

Answer 11

C5b, C6, C7, C8 and C9 bind together and the C9 molecules then form pores in the membrane

Question 12

how does the MAC cause phagocytosis?

Answer 12

C3b enhances phagocytosis by opsonisation by attaching to the receptors on the phagocyte

Question 13

how is inflammation caused by the MAC?

Answer 13

C3a stimulates mast cells to release histamine, C5a activates phagocytes and attracts them to the infection

Question 14

how are neutrophils activated in acute inflammation?

Answer 14

by endothelium cells lining the blood vessels

Question 15

what is different about activated neutrophils?

Answer 15

have increased receptors for chemo attractants

Question 16

what increases when neutrophils are activated?

Answer 16

metabolic activity which causes a release of oxygen and nitrogen intermediates which kills pathogens

Question 17

what limits the damage caused by inflammation?

Answer 17

regulation of duration and intensity and fibroblasts stimulated to produce ECM for tissue repair

Question 18

how does the acute inflammatory response begin?

Answer 18

bacteria enters and causes damage, causing mast cells to release histamine

Question 19

what is oedema?

Answer 19

excess of watery fluid collecting in the tissues

Question 20

what happens due to increased permeability of blood vessel?

Answer 20

plasma proteins enter the arteriole which activates complement

Question 21

what causes the killing of bacteria in acute inflammation?

Answer 21

chemotaxis of neutrophils causing phagocytosis and lysis via the MAC

Question 22

what is extravisation?

Answer 22

in order for neutrophils to enter infected tissues, they need to pass through endothelial cells using CAM’s

Question 23

what are interferons?

Answer 23

proteins produced by certain types of cells that have been infected by viruses

Question 24

what do interferons do?

Answer 24

inhibit viral replication

Question 25

what are type 1 interferons?

Answer 25

alpha and beta interferons which suppress tumours and metastasis, part of natural immunity

Question 26

what are type 2 interferons?

Answer 26

gamma interferons, secreted by NK and Tc cells, part of aquired immunity

Question 27

what do type 2 interferons do?

Answer 27

activates neutrophils and macrophages

Question 28

what is the actions of interferons?

Answer 28

released by infected cells, diffuse into neighbouring cells and bind to surface receptors

Question 29

what do interferons stimulate?

Answer 29

the synthesis of anti-viral proteins that inhibit viral replication

Question 30

what are NK cells?

Answer 30

population of lymphocytes similar to Tc cells

Question 31

where are NK cells found?

Answer 31

lymph nodes, spleen, bone marrow and the blood

Question 32

how do NK cells kill cells?

Answer 32

by cytolysis and induce apoptosis, secrete perforinsm respond to and produce interferons

Question 33

what are defensins?

Answer 33

present in immune and epithelial cells, form pores in target cells

Question 34

where are pattern recognition receptors found?

Answer 34

innate immune cells and epithelial cells

Question 35

what do pattern recognition receptors recognise?

Answer 35

damage associated molecular patterns and pathogen associated molecular patterns

Question 36

what does binding to pattern receptors cause?

Answer 36

release of inflammatory cytokines

Question 37

what is the acute phase response?

Answer 37

systemic response that causes a rapid rise in acute phase proteins after an infection

Question 38

what is the role of the acute phase response?

Answer 38

proteins such as C-reactive protein binds to bacterial phospholipids, activates complement and promotes phagocytosis

Question 39

what is the acute phase response activated by?

Answer 39

cytokines from macrophages