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Flashcards in Foundations in Immunology Deck (75):
1

Whats a pathogen?

Any microorganism that causes harm

2

What are physical barriers to pathogens?

Skin
Reproduction, respiratory and digestive tracks

3

Describe the innate immune system...

Non-specific
First to come into play
Will produce the same response time and again – no memory

4

Describe the adaptive immune system...

Highly specific
Involves antibody Production
Has immunological memory

5

Give an example of an innate response.

Splinter enters foot
Area around splinter gets red and swollen
Macrophages flood area

6

Where Do Macrophages Come From?

Bone Marrow
Monocytes differentiate into them

7

How to macrophages work?

Mø give off chemicals that restrict blood flow away from site of injury (redness)

Contraction of endothelial cells (swelling)

Produce Cytokines to alert other cells to the ‘danger’ and induce them to travel to the site of injury

8

What is the main role of the immune system and what does it employ?

Bodies 1st line of defense

Uses physical barriers - tight junctions between epithelum and mucous membranes

Uses phagocytic cells like macrophages and neutrophils

Uses soluble factors
-Growth and Enzyme inhibitors
-Lysins
-Complement proteins

9

Describe phagocytosis...

Phagocytosis is triggered when the phagocyte recognises a foreign cell.

It is the internalization of foreign matter by cells into cytoplasmic vesicles. Once inside, the matter is digested by lysosomes, which contain enzymes

This also kills the phagocytic cell that did the ingesting.

10

What are the 3 activation pathways of the complement system?

Classical
Alternative
Lectin

11

Briefly describe the complement system.

The complement system consists of about 20 individual proteins which act together in an enzyme cascade to form a membrane attack complex

This makes a hole in the pathogen (bacterium) which disrupts the ability of the pathogen to maintain homeostasis and it dies.

12

What do all 3 pathways always end up with?

C5 convertase

13

What two pathways are effector mechanisms of the innate immune system?

Alternative and Lectin

14

What pathway is an effector mechanism of the adaptive immune system?

Classical

15

What happens with the C5 convertase?

It cleaves C5, which goes on to comine with C6, C7, C8 and C9 to form a MAC.

C5-8 forms the stalk and C9 forms the pore which causes cell cysis - poking hole in the cell.

16

What does the complement system achieve?

Opsonisation of invaders

C3a and C5a (bits that were cleaved) act as chemoattractants

17

Functions of the complement system?

Lysis of microbes
Promotes phagocytosis of microbes
Stimulates inflammation - activating mast cells and neutrophils
Also stimulate activation of B Cells and Ab production

18

What stops NK cells targeting our own cells?

Our cells have MHC class 1 proteins which signal to it that its our cells

19

Whats a cytokine?

Chemicals used by cells to communicate with other cells

20

Function of the lymphatic system?

Drainage of tissue
Absorption and transport of fatty acids
Immunity

21

Differences between lymphatic and blood vessels?

Lymphatic vessels are blind ended cells

Lymph vessels only carry fluid away from tissues unlike blood

22

What are the 3 phases of immune defence?

Recognition of danger
Production of specific weapons
Transport of weapons to site of attack

23

Where are blood cells produced and what type of organs are they?

Bone marrow and thymus
Primary lymphoid organs

24

What is hematopoiesis?

Formation and activation of blood cells

25

Function of the thymus?

T-cell education

26

Function of secondary lymphoid organs?

Site of lymphocyte activation by antigens

27

What 2 areas is the spleen divided into?

Red and white pulp

28

Function of spleen?

Filtration of blood

29

What separates red and white pulp?

Marginal zone

30

What is a high endothelial venule?

Simple columnar cells line venules,

They are slightly looser than normal venules, which allows fluid and lymphocytes to leak out of the blood vessels.

31

What two zones are lymph nodes separated into?

B and T zones

32

What effect does B cells have on T cells?

Cause B cells to make antibodies

33

What are peyers patches?

Patches of smooth cells embedded in villi covered cells

34

What does MALT stand for and what is it an example of?

Mucosal Associated Lymphoid Tissue - a peyers patch

35

What covers peyers patches?

M cells

36

Difference between adaptive and innate immune systems?

Adaptive is very specific and has immunological memory

37

How does the adaptive immune system display a much larger response to an antigen in repeated exposure?

Presence of memory cells allow a much quicker and stronger response after primary exposure

38

What are the differences between active and passive immunity?

Active immunity - conferred by a host response to a microbe or a microbial antigen

Passive immunity - conferred by adoptive transfer of antibodies or T lymphocytes specific for the microbe

Active immunity is the only one that generates immunological memory

39

Why does passive immunity not have memory?

Because it isn't your own B cells creating the response

40

Where are B cells made?

Bone marrow

41

What is the antigen receptor for a B cell

Surface immunoglobulin

42

Why is it more important to tolerize T cells than B cells?

B cells cannot make antibodies in response to most antigens without the help of T cells

43

What part of the pathogen are antibodies specific to?

The epitope

44

What induces B cells to multiply?

Recognition of a specific epitope on a specific antigen on a specific pathogen

45

What 2 chains are antibodies separated into?

Light and Heavy chain

46

What modification is made to antibodies after B cells multiply and produce them?

The antibodies will have a much higher affinity for the epitope being targeted

47

What chain does the antibody bind to?

Light chain

48

What chain does the cell bind to?

heavy chain

49

What do the heavy chains define?

The classes of immunoglobulin

50

What are the classes of antibody?

1. IGM
2. IGD
3. IGA
4. IGE
5.IGG

51

Function of IGM?

Fixes compliment and oponization

52

Function of IGG?

Good opsonizer

53

Function of IGA

Protects mucosal surfaces, resistant to stomach acid

54

Function of IGE?

Defends against parasites, cause anaphylactic shock and allergies

55

What causes antibodies to be flexible?

Presence of a hinge between the light and heavy chains

56

Why does antigen bound IGM display good complement binding?

Binding to epitope causes a conformational change that allows c1 protein to bind to IgM

57

What actually is opsonisation?

The process of "tagging" a pathogen which causes fc receptors to "stick up" which causes the pathogen to be more susceptible to phagocytic action

58

Why is it that mast cells can cause allergic reactions?

When mast cells encounter a pathogen they dump all of their contents onto the pathogen to neutralise it, some of these contents can cause an allergic reaction in the host

59

What are the different ways to activate a B cell?

T cell dependent and T cell independent complement activation

60

Describe how T-cell dependent activation works.

Signal from a clustered BCR (a surface IGM) along with a signal from a T cell in which a protein on the surface of a T cell recognises the same antigen as the B cell and then binds to a receptor on the B cell

61

Where are T cells educated?

Thymus

62

What is the cell surface receptor in a T cell called

T cell receptor

63

What conditions have to be met in order for a T cell receptor to recognise antigens?

Has to be bound to a MHC protein

64

What 2 classes of T cells are there?

Helper CD4+
Cytotoxic CD8+

65

What types of antigens can T cells recognise?

ANY protein peptide that a pathogen may have due to association with MHC

66

What is it important for all lymphocytes to learn to do with regard to "self"

Do not recognise the self antigen

67

What happens to T cells that are unable to interact with MHC molecules or cannot distinguish self from non self

Death by apoptosis

68

What determines what type of T cell thymocytes develop into?

Whether it binds to MHC 1 (cytotoxic) or MHC 2 (helper)

69

Purpose of MHC 1?

Presents virally induced peptides to CD8+ T cells and trigger cytotoxic response

70

Purpose of MHC 2

Presents exogenously produced Ag to CD4+ T cells and activate macrophages and B cells

71

where is MHC 2 found

On antigen presenting cells

72

What deciees which T cell a naive T cell turns into after MHC peptide recognition?

A range of different chemicals acting on the T cells

73

Can helper T cells destroy pathogens?

No

74

What do cytotoxic T cells release once exposed to infected/dysfunctional somatic cells?

Perforin, which forms pores in the target cell, also releases granzyme B - induces apoptosis

75

How can T memory cells be formed?

Can arise from fully differentiated cells or from partially differentiated cells.