Innate immunity Flashcards

1
Q

Why do we need an immune response?

A

Prevent infections and cancers

Remove dead/non-functioning components

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2
Q

Physical barriers

A
Skin
Cilia
Hairs
Mucus
Flushing action of tears/urine
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3
Q

Characteristics of viruses

A

Obligate intracellular pathogen

20-800 nm

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4
Q

Characteristics of bacteria

A

Prokaryote

0.2-20 micrometers

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5
Q

Characteristics of fungi

A

Eukaryote

2 micrometers to a centimetre

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6
Q

Characteristics of a protozoal parasite

A

Two or more hosts

10-200 micrometers

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7
Q

Characteristics of multicellular parasites

A

Multiple lifestyles

1 cm to 3 m

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8
Q

What is desquamination?

A

Constant turnover of skin cells

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9
Q

What do goblet cells do?

A

Produce mucus

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10
Q

Which cells are part of gastric immunity?

A

Goblet and dendritic cells

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11
Q

Chemical defences of the body

A

Lysozymes
Normal flora
Stomach acid

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12
Q

Why is normal flora beneficial?

A

Gets rid of pathogens and stops them binding

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13
Q

What is the order of defence in the body?

A

1st line - physical barriers
2nd line - innate immune system
3rd line - adaptive immune system

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14
Q

What do all cells in the innate immune system start as?

A

Pluripotent stem cell

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15
Q

Which cell do most defence cells come from?

A

Myeloid progenitor

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16
Q

What do granulocytes do?

A

Degranulate contents to fight pathogens

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17
Q

What do neutrophils do?

A

Phagocytosis

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18
Q

What do basophils do?

A

Granulocyte, similar to neutrophil

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19
Q

What do monocytes do?

A

In tissue, they differentiate into macrophages

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20
Q

What do megakaryocytes do?

A

Produce platelets/phagocytose/present antigensW

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21
Q

What do mast cells do?

A

Initiate inflammatory immune response

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22
Q

What do dendritic cells do?

A

Present antigens

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23
Q

Where do cells in the adaptive immune system come from?

A

Lymphoid progenitor

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24
Q

Characteristics of mast cells

A

Granulocyte
Large nucleus
Signals from DAMP/PAMP
Releases granules

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25
Q

What do the granules released from mast cells do?

A

Recruit immune cells
Regulates phagocytosis
Repairs tissues
Vascular permeability

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26
Q

What impact do mast cells have on vasculature during inflammation?

A

Cause vasodilation in smooth muscle cells
Makes blood vessels leaky and swell
Endothelial cells have adhesion molecules activated by mast cells and they get sticky. This is where WBCs bind to enter tissue
Plasma proteins leak into tissue to fight infection

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27
Q

Symptoms of inflammation

A

Rubor/calor
Dolor
Swelling

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28
Q

What do dendritic cells do?

A

Pick up pathogens in tissue and travel to lymph node
Present pathogen to immature T-cells to activate them
Activates T-cells and coordinates correct immune response

29
Q

How are T-cells drawn to the site of an infection?

A

Cytokines

30
Q

What is chemotaxis?

A

Movement along gradient of increasing concentration of the attractant

31
Q

How many nuclei do neutrophils have?

A

Multiple

32
Q

What do neutrophils do?

A

Phagocytose pathogens

Respiratory burst

33
Q

How are leukocytes recruited to an area?

A

Follow chemotactic gradient
Adhesion molecules are activated and become sticky
Receptors bind to adhesion molecules
Slow down leukocyte until bound to endothelial cells
Gaps in tight junctions allow neutrophils to enter tissues

34
Q

How does phagocytosis occur?

A

Immune cell attaches to pathogen by recognition receptors
Pseudopodia wraps around pathogen
Neutrophil degranulates

35
Q

What is a respiratory burst?

A

Free radicals produced to break down pathogens
E.g. after opsonin/ligand binding to cell surface receptors, the NADPH oxidase generates superoxide (O2.) in phagocytes. Superoxide dissimulates into H2O2, which reacts with chloride ions to form hypochlorous acid (HOCl) catalyzed by myeloperoxidase

36
Q

Which cells can present antigens?

A

Macrophages
Dendritic cells
B-cells

37
Q

What do macrophages do?

A

Phagocytosis
Respiratory burst
Present antigens and take to lymph nodes to inform about infection

38
Q

Where do NK cells come from?

A

Lymphoid

39
Q

Why are NK cells classified as innate?

A

They don’t need to be activated

40
Q

How do NK cells kill pathogens?

A

They have ‘death-receptors’ on membrane which bind to ‘death receptor’ ligands on pathogen. When bound, Nk cell degranulates to break down cell by apoptosis

41
Q

Function of NK cells

A

Activate macrophages
Death receptors
Release cytokines to communicate with other cells

42
Q

Which is the rarest granulocyte?

A

Basophil

43
Q

What do basophils do?

A

Acute and chronic allergic response

Contribute to resistance to internal parasites

44
Q

Why do basophils have their name?

A

Take up basic dyes

45
Q

Where are eosinophils mainly found?

A

Gut and lymphatic system

46
Q

Why do eosinophils appear pink under a microscope?

A

Take up acidic dye eosin

47
Q

What do eosinophils do?

A

Participate in allergic disease and helminth infections

Release cytokines to attract cells of immune system

48
Q

What is pattern recognition?

A

PRR receptors on surface of innate cells
PRR recognise PAMP
Adaptive cells use antibodies and t-cell receptors to recognise PAMP

49
Q

What does PAMP stand for?

A

Pathogen Associated Molecular Pattern

50
Q

Examples of PAMP in bacteria

A

Peptidoglycan
Lipiprotein
Flagellum
DNA

51
Q

Examples of PAMP on viruses

A

DNA

RNA

52
Q

What does TLR stand for?

A

Toll-like receptors

53
Q

Where are TLRs expressed from?

A

Macrophages

Dendritic cells

54
Q

What do TLRs do?

A

Recognise different pathogens

Activate APCs to produce pro-inflammatory cytokines and stimulate co-stimulatory molecule expression

55
Q

What is another name for TLRs?

A

PRR

56
Q

Where is C-reactive protein produced?

A

Liver

57
Q

What type of protein is c-reactive protein?

A

Acute phase protein

58
Q

What can CRP level be used to measure?

A

Inflammation

59
Q

What does CRP do?

A

Enters tissue and activates immune cells/opsonize pathogen to make it more visible to the immune system

60
Q

What are the three pathways in the complement protein cascade?

A

Lectin
Classical
Alternative

61
Q

What is the lectin pathway in the complement protein cascade?

A

Iniated by lectin binding proteins and ficolin MASP binding to carbohydrates on pathogens
Produces C3 convertase

62
Q

What is the classical pathway in the complement protein cascade?

A

Initiated by C1Q binding to pathogen. Produces C3 convertase

63
Q

What is the alternative pathway in the complement protein cascade?

A

C3 complement protein binds to carbohydrate on pathogen surface
C3b produced, which binds with other factors to produce C3 convertase

64
Q

What do complement proteins do?

A

Means our cells are lysed - membrane attack complex forms (complement protein makes holes in target cell)
Activates inflammatory response and membrane attack complex
Act as signalling molecule
Cell clearance

65
Q

What happens when a pathogen is opsonised?

A

Makes it more visible to innate cells

66
Q

What happens when a membrane attack complex is formed?

A

Pores formed in surface of pathogen so it bursts and loses its contents

67
Q

Antimicrobial proteins in the innate immune system

A

Antibodies/lytic enzymes/interferons/cytotoxins

complement

68
Q

Inflammatory proteins in the innate immune system

A

Cytokines/chemokines/histamines

69
Q

What is the common end product of the complement system?

A

C3 convertase