Innate immunity 2

Question 1

What types of response is inflammatory

Answer 1

Innate

Question 2

What causes an inflammatory response

Answer 2

Microorganisms entering the body through skin.

Question 3

What types of cells are involved in inflammation

Answer 3

Mast cells

Neutrophils

Question 4

Describe how inflammation works

Answer 4

Mast cells (in tissue) release chemical signals to attract other cells. Neutrophils enter blood from bone marrow and cling to capillary walls. The signals tell the blood to slow down neutrophils, to dilate and become ‘leakier’. Neutrophils leak through to tissue (diapedesis) and follow trail to injury site.

Question 5

What is diapedesis

Answer 5

When neutrophils ‘leak’ out of capillaries into tissue

Question 6

What is a brief overview of stages of phagocytosis

Answer 6

1 - labelling
2- Engulfing
3 - Fusing
4 - Digesting
5 - exocytosis

Question 7

Describe stage 1 - labelling

Answer 7

Antibodies label what should be eaten (opsonisation). Phagocyte adheres to pathogen

Question 8

Describe stage 2 - engulfing

Answer 8

Forms pseudopods that engulfs pathogen in phagocytic vesicle

Question 9

Describe stage 3 - fusing

Answer 9

Phagocytic vesicle fuses with lysosome vesicle to form a phagolysosome

Question 10

Describe stage 4 - digesting

Answer 10

Toxic compounds and lysosomal enzymes digest/destroy pathogens

Question 11

Describe stage 5 - exocytosis

Answer 11

Exocytosis of vesicles removes indigestible residue.

Question 12

How does the lysosome digest the pathogen

Answer 12

Low pH - acidic environment. Produce reactive oxygen (hydrogen peroxide) and reactive nitrogen (nitric oxide). Filled with enzymes

Question 13

What enzymes do lysosomes contain

Answer 13

Protease - digests proteins
Lipase - digests lipids
Nuclease - digests nucleic acid

Question 14

What is the complement cascade

Answer 14

Series of enzymatic reactions to clear pathogens from blood and tissue. 9 major protein complexes

Question 15

What does the complement system do

Answer 15

Labels pathogens (opsonisation)
Recruits phagocytes (chemotaxis)
Destroys pathogens (lysis)

Question 16

What are the 3 complementary pathways

Answer 16

Classical - Antibody and complement bound to pathogen
Alternative - complement binds directly to Pathogen surface
Lectin - Carbohydrate components of microbes directly binds to complement

Question 17

Where do the pathways converge

Answer 17

Amplification (C3 convertase)

Question 18

What are the 3 complementary outcomes

Answer 18

Label - Labels pathogens bound to complement for phagocytosis.
Destroy - Membrane attacks complex (MAC) forms pores in bacteria cell
Recruit - Act as peptide mediators of inflammation and recruit phagocytes.

Question 19

Describe label outcome of complementary

Answer 19

Opsonisation - coats microbe with antibody and/ or complement C3a fragment

Question 20

Describe Destroy outcome of complementary

Answer 20

Microbes coated with C3b are phagocytosed. MACs causes lysis - making a hole in bacteria cells so it looses its nutrients and dies

Question 21

Describe recruit outcome of complementary

Answer 21

Attracts phagocytes to site - Mast cells degranulated by C3a and C5a to release mediators.